Category Archives: Programming language

Programming language is a formal language designed to perform processes that can be carried out by machines

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Javascript data types

Javascript data types

Types in Javascript are a representation of data because it does not require variables to declare their type, because all types are automatically converted

Type boolean

The Boolean type simply distinguishes between two states, a success or enabled state, true value, true, and a failure or deactivated state, false value, false

Numeric types

The numeric types can be divided into real and integer

Type integer numeric

  • Decimal

    integer base 10

    Both positive and negative

  • Hexadecimal

    integer base 16

    Placed before the base number 16 0x or 0X

  • Octal

    integer base 8

    We place a zero before the number in octal

Numeric type real

The actual is made up of a whole part and the other fractional separated by a point of the previous

The fractional part can be composed by an indicator of exponent E or E followed by an integer that indicates the value of the exponent

Type string

A string is a string of characters delimited by quotation marks

The quotation marks will be single or double according to a particular rule

The default is to use double quotation marks ("), but if any statement to be included in those quotation marks, if that statement contains a string or in turn another statement that must also be delimited by those quotation marks, these quotation marks will then be single quotation marks (')

On the other hand, we must take into account the writing of special characters in what we call escape sequences

The escape sequence always begins with the character \ and then another character is written that represents the special code or the number in octal or hexadecimal of its ASCII code

Escape sequences represent a single character in the strings in which they appear

Code Description
a Sound
b White
f Line break
n New line
r Carriage return
v Vertical tab
\ Blackslash "\"
‘ Single quotation mark
" Double quotation mark
Ooo Ascii in octal
Xhh Ascii in hexadecimal
t Horizontal tab

Arrays

We can create arrays that we will give a name and that we will access with an index that will start from element number 1 (not from 0 as in Java or in C / C++)

In the arrays as with variables, there are no default types

To create an array it is necessary to define a function like the one below:

Comment on the function that the reserved word this refers to the current variable, that is, the variable that will contain the array

On the other hand, to observe that arrays have a length property that shows us the length of that array

Finally show the use of this function:

Objects

Objects consist of a set of values, properties, and a set of methods applied to those values

It is these methods that allow us to modify the state of that object, that is, the value of its properties

In JavaScript there are predefined objects

In addition, the programmer can also create his own objects

To make use of the properties of an object, simply use the following notation:

my_object.property

This will be seen more clearly in the following example, in which we have a University object in which we have the properties: Name, Last Name, Age and Faculty

Assuming we have a Uni1 variable that contains a University object at any given time:

But not only can we access the properties of an object by using the notation above, because, there is a relationship between objects and arrays, since we can access an object as if this were an array and its elements were the properties of object in the order in which they were defined

This type of vectors are referred to as associative arrays

A method it is a function assigned to an object

The following syntax is used to assign a function as a method of an object:

We can observe that the name of the method is the way in which we want to name the function within the object

A method can be called in a context using the syntax:

Object.methodName(parameters);

The reserved word this allows us to reference the current object

For example, suppose that the validate function allows you to validate the properties of an object through an associated minimum and maximum; we will have:

You may call then the function validate to change the values of a form by using the reserved word this and the attribute OnChange to detect the changes of values

This is done through the HTML flag and the event:

In general, the word this refers to the current object

The client and the server have a set of predefined objects that can be completed using new objects. The creation of an object is done in two stages:

  1. The object is defined by a function
  2. Create an object using the reserved word new

To define an object, a function will be created to specify its name, its functions and its associated methods

For example, if you want to create a university object whose properties would be name, surname, age and DNI, the following generic function will be defined:

The object instance will be created as follows:

The properties of an object can be described by other objects

We make the university object have a property of the Note_Mean object therefore:

Therefore, to access the final note:

student.expedient.final

When an object is defined, it is possible to enrich its description through new properties

student.dni = 44567234;

Now the property id belongs to the instance of the object contained in the student

This modification will not affect the other objects of the university type, since to add a property to an object type it must appear in its definition

The definition of methods associated with an object can be specified in the object definition

For example, for the university object we define a function that shows the name, surname, DNI and faculty of a student

This function becomes a method associated to the type by performing in its definition the following:

Its use will be:

student.Data();

The following example shows the function of the type of university that we have created

To do this we create the following form:

The Show_Univers (form) function is defined as follows:


Average mark of the academic stage



Note Have not checked if the data that is inserted in the form are "correct", that is, if the notes are between 0 and 10, if the first and last names are composed only of letters or the age is numerical

Null value

In JavaScript variables can be assigned a value that indicates the empty value, this value is null

The conversion of data types

First of all, remember that JavaScript doesn't need type declaration

The contents of the variable will be converted automatically in the course of the programme according to its use

The type conversion scheme is based on the following principle: the associated type corresponds to that of the left operand

This is because the evaluation is done from left to right

For example, suppose you define the following variables:

If we evaluate the following expressions

The first expression will convert the a_number variable to a character string because the operand on the left an_string is a string of characters

This expression concatenates the two character strings and the result of x is:"742"

Conversely, the second expression converts the string an_string to a numeric value because the left operand a_number, is as its own name indicates, a number

This second expression sums the two numbers and the result of y is: 49

Type conversion cannot be done in all possible cases: certain character strings cannot be converted to number

Such conversions fail with an error

For example:

Table that summarizes type conversion in JavaScript:

Type Function Object Number Boolean String
Function — Function Error Error Descompila
Object Error — Error True ToString
Null object FunObj ok — 0 False “null”
Number Error Number — True ToString
Number = 0 Error Null — False “0”
Boolean = true Error Boolean 1 — “true”
Boolean = false Error Boolean 0 — “false”
String Single quotation mark String Numstr ok True —
String null Error String Error False —
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Control structures in Javascript

Control structures in Javascript

For control structures, JavaScript has the typical control sentences of high level languages

Variable statement

Variables in JavaScript are not assigned a predefined type

In JavaScript the type of the variables depends on the value that contain the same in each time

Therefore it performs an automatic conversion of types

JavaScript recognizes the following types of values:

Since there are no types of a priori variables, we do not have to specify the type of variable when declaring it

The declaration of variables is done by prepending the reserved word var to the name of the variable

It is possible to assign the value when we declare

The if sentence

The if sentence has the form:

The parentheses associated that define the condition are not optional

If the condition is true, instruction 1 will be executed; otherwise it is executed if there is instructution 2

The use of the sentence else is optional, so brackets have been used in the definition

If omitted, the instruction block will only be considered when the condition is true

A block of instructions is a set of instructions bounded by curly brackets

Keys after sentencing if are not required

If omitted and the condition was true, the following instruction will be executed

Otherwise, the subsequent instruction will be executed, independent of the condition state

Thus, the omission of keys after the sentence if it will allow us to write everything on a single line finished in ;

The else if sentence

We can also use sentences if anities by sentencing else if

Sentences else if work just like a sentence if

But they will only be executed in case the condition of the sentence if was false

The switch sentence

Makes is select a group of sentence among several possible

It is an alternative to the use of sentences else if anities

Its syntax is:

The expression between parentheses of the switch must be whole

Your result will be compared with the different values of the case

If it matches one of them, the following sentence will be moved to the case with that value and consecutive instructions will continue to be executed until a sentence is found break or reach the switch lock keys

In case the result of the expression does not match any value, execution will be passed to the next statement sentence on the label default, if there were, and it will continue as a case

The values in the case can be a constant expression

There can be two case with the same value

The while sentence

The while sentence has the form

The parentheses are not optional

If the condition is met, the sentence or instruction block is executed and the process is repeated until the condition is no longer met

The do sentence

The do sentence has the form

It's very similar to the sentence while, except that the condition goes after the instruction or block of instructions

So they are executed at least once even if the condition is false

The for sentence

As for such a sentence, in JavaScript we can distinguish two variants:

  • The loop for "classic"
  • The loops for / in

The loop for "classic"

This loop has a syntax very similar to that of C / C+

In this syntax:

Initialization creates the counter variable and gives it an initial value

Condition must be fulfilled for the loop to run

Depends on the variable index

Expression updates the value of the variable index

The equivalent of this while expression is:

The loops for / in

This loop has a syntax very similar to the for-each Java

Iterates a variable var over all the properties of an object obj that is passed to it

Thus, for each value of var is is executed, the judgments of the loop

Therefore, the loop will have as many iterations as the object's properties, and in each iteration the variable will have the value of the corresponding object's property with that iteration

Its syntax is:

The break sentence

The break sentence can be placed within a loop or anities loops

When you execute the break sentence exits the loop more internal

To all effects, the break sentence acts as a jump to the sentence following the loop in which it runs

The continue sentence

The continue sentence does not leave the loop but causes the next iteration to run

In the loop while the execution of the continue causes the program flow to jump to the condition

In the for loop the continue execution causes the increment expression to run, and then continue normally with the condition

That is, running the continue prevents the rest of the loop body from running

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Functions in Javascript

Functions

To define functions we have the instruction function

After this reserved word is placed the name of the function followed by a list of arguments delimited by parentheses and separated by commas

The return statement

The statement return it is the one that allows you to return the result of a function

The example shows a function that returns the area of a square of side l

Properties of the functions

JavaScript associates two properties with each function:

  • arguments
    it allows the management of the optional parameters
  • caller
    identifies the function that made the call

The property arguments

Is an array that contains the parameters that are passed to the function

In the example we have defined the Sum function to calculate the sum of the numbers passed as arguments

Thus, Sum(4,5,7) returns 16 and Sum(56) returns 56

The caller property

Displays the name of the calling function, so this property will return a string of characters

Considerations to be taken into account

Before you start working with features, you need to consider the following points:

  • The JavaScript language does not allow the definitions of nested functions

  • The passing of parameters is done by value

    That is, if a function modifies the content of its arguments, this modification is local and does not affect either globally or the function made the call

Functions are predefined by the language

Eval function

Has as argument an expression and returns the value of the same

This function is useful to evaluate a string of characters that represents a numeric expression

The issue was effected through a form field is a string of characters that it is sometimes necessary to convert to a numeric value

The following example illustrates how allowing the user to enter a numeric expression you can visualize it as the value of the expression

If you haven't entered anything, you see undefined and if it's not a numerical expression, it doesn't make changes to the visualization


Functions escape and unescape

These two functions allow you to encode strings in URL format

This encoding is necessary in the automatic creation of hypertext links or in the definition of persistent properties as the Cookies

Function isNaN

Function that checks if the value passed for the parameter is numeric or not

The result of this function is a Boolean

That is, it evaluates an argument to see if it is NaN: (Not a Number)


Function parseFloat

Converts a string of characters to a floating-point number

If a non number character is found, the sign '+', '-' or exponent, returns the value found up to that point

Similarly, if the first character cannot be converted to number it will return zero


Function parseInt

Converts a string of characters to an integer number with a specified base

La base puede ser 8, 10 ó 16

If a non number character is found, the sign '+', '-' or exponent, returns the value found up to that point

Similarly, if the first character cannot be converted to number it will return zero

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jQuery

jQuery

jQuery is a library of free software written in Javascript, with MIT License and GNU General Public v2, allows its use in open source projects and private

In line with the principle type less, do more

To achieve this, it allows you to write Javascript code in a simpler way, doing in a single call tasks that requeririan several lines of code

Simplifies many of the tereas common, such as the handling of the DOM, CSS properties and an AJAX call, in addition to allowing the creation of effects or animations

Installation

Download the library in its most stable version from their official website jQuery.com

We load the library in the head of our HTML code:

In the example, version is the current number of version, may vary at the time of your download

It is advisable that in production you use the version min, since it is optimized for faster loading in the browser

There are also repositories CDN third-party that can be viewed on the official website of downloads, us librarian of having to update the current version of the library

However, we run the risk of having security flaws if someone outside of the introduction of malicious code in those repositories, or remain inacesibles for any reason

To include them simply modificariamos the src with the url of the repository CDN to indicate to us

Load the code

We can typically include the code of jQuery inside a script block like we do with Javascript, or use an external file .js where we include our own code

To be able to execute our instructions will be useful that the DOM of our HTML has been completely loaded, but we can execute them before that happens

In the example we have opted to load the DOM tree when it has loaded the HTML completely, including our code inside of the curly braces

In this other example we have an equivalent version that allows us to write less code, choose the one you like the most, although the first is more clear

Basic syntax

The jQuery syntax is very similar to CSS because all of the calls are composed of a selector followed by a call

In the example we can see the $ symbol that allows us to access the elements of jQuery

The selector will allow to select specific elements within the DOM tree

The action will be a function that allows us to interact with the item selected by the selector

In the examples we have the operator this, which represents the current item selected

‘p’ a tag is HTML valid, which represents an element, here we will be able to use any of them to perform searches

When we see with more detail the selectors, we will deepen in how they should be those searches

‘.test’ uses the symbol . to refer to what follows after that is a class, in this case, the test class

‘#test’ use the # symbol to refer to that what follows is an id, in this case, the id test

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Selector

Selector

A selector allows us to specify what elements we want to apply the action

There are the following types of selector:

  • Item
  • Class
  • Id

Item

It is possible to select an element directly according to their type of HTML tag

In this example we have selected all of the elements of type paragraph

In this example will be hidden all the elements of type paragraph when you press on the item type button

Class

It is used with the symbol . and allows us to select elements with a specific class

In this example we have selected the element of the test class

In this example will be hidden all the elements of the test class when you press on the item type button

Id

Used with the # symbol and allows us to select elements with an id specific

In this example we have selected the element with the id test

In this example will be hidden all the elements with the id test when you press the element type button

Practical example

More examples of selector

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Events

Events

The actions that the user performs or the changes you make in the page are known under the name of events

An event is the sign that 'something' has happened

Syntax of events

You need to specify a selector, to know which element the event will interact with, followed by the event in parentheses

We will use the following sample HTML, that contains a simple form, to get to know the use of the events, accompanied by a file that we will call event.js

To process the form, we have also added a file form.php however, we are not going to use the examples on events

Item events

This type of event is that normally used by the user to interact with the elements of the HTML, when you hover the mouse over the element or is pressed, among others

Among the most important of which we highlight:

  • focus

    is triggered when the focus goes to the element

  • blur

    is triggered when the focus goes to another element or lose it

  • click

    is activated when you click on the element

  • dblclick

    is activated when you double click on the element

In the example we have selected the element with the id button, and responds to the click event that has as a parameter the variable warning

It could have included the code inside the click event, but wanted to emphasize that the parameters can be a variable that contains a function, so we can have different variables with different behavior, without having to modify our code

Mouse events

Occur when the user uses the mouse within the HTML document or any of the elements that compose it

Among the most important of which we highlight:

  • mousedown

    turns on when you press a mouse button

  • mouseup

    is activated when you stop pressing a mouse button

  • mousemove

    is triggered when the mouse moves

  • mouseover

    is triggered when the mouse moves over an item (when we enter in the item)

  • mouseout

    is triggered when the mouse leaves the element (when we leave the element)

In the example, we have added a couple of events that change the type of letter when you pass the mouse over the element with id button

It is possible to assign to these event parameters that contain information about a mouse event

Among the most important of which we highlight:

  • screenX and screenY

    represent the coordinates of the mouse pointer with respect to the global coordinates of the screen

  • clientX and clientY

    represent the coordinates of the mouse pointer with respect to the browser window

  • button

    is the number of the button that has been pressed (left = 0, center = 1, right = 2)

    If you do not want to pass it as a parameter, we can use the property buttonsthat includes more buttons, as the mouse wheel or the forward and back buttons of the browser

In the example we have modified the variable warning to detect which button has been clicked and what position you had the mouse on the screen, when it has been clicked

Keyboard events

Occur when the user uses the keyboard

Among the most important of which we highlight:

  • keydown

    turns on when you press a key

  • keyup

    is activated when you stop pressing a key

  • keypress

    is activated when you press and stops the press of a key

It is possible to assign to these event parameters that contain information about the event from the keyboard

Among the most important of which we highlight:

  • char or charCode

    is a string with the character that has been pressed (provided that the same is representable)

  • key or keyCode

    it is an identifier that represents the key that has been pressed

    You can see the complete list on the page for developers Mozilla

  • ctrlKey,, shitKey and altKey

    these are fields that indicate whether the key Control, Shift or Alt key had been pressed when the event occurred keyboard

In the example has been added to the variable key with parameters to capture the keystrokes when you type in the element with the id login, and has modified the set of calls to use, using the keypress event

Touch events

These events are produced by touching a touch screen

Are similar to those produced by a mouse, but its delay is much lower

Because of this, conflicts can occur with mouse events, this is why it is advisable to disable them, not to run similar events twice

Among the most important of which we highlight:

  • touchstart

    is activated when the finger touches the surface of the screen

  • touchend

    is activated when the finger stops pressing the surface of the screen

  • touchmove events

    is activated when the finger slides on the surface of the screen

  • touchenter

    is activated when the finger is moved over an item (when we enter in the item)

  • touchleave

    is triggered when the finger leaves the element (when we leave the element)

  • touchcancel

    is activated when the finger goes outside the bounds of the browser window

Form events

The forms have their own events, among the most important of which we highlight:

  • click

    it is activated when we click the mouse on an item
    It is usually used with buttons (button, submit)

  • change

    is triggered when the user modifies the value of a text element

    This is normally used with input of type text, textarea or drop-down lists to select an option

  • focus

    is activated when the user selects a form element

  • blur

    is triggered when the user moves to another form element

  • submit

    is activated when the user performs the action of submitting the form (not just when pressed the button submit, which can be simulated at the push of a button which makes the time of submit or when you force a call to the event from another event)

    In addition, the submit event generates the events mousedown, click, mouseup and submitin that same order, which allows us to perform validations on the form elements before final submission

  • reset

    is activated when the user performs the action of resetting the form (not only when you press the reset button, which can be simulated at the push of a button that makes the times of reset, or when force a call to the event from another event)

In the example, we have added the variables to send (to validate the fields login and pass) and write (to validate that it does not enter the @ symbol into the field, pass); has modified the set of calls to use, using the events submit and change

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Modification of styles

Modification of styles

JQuery allows to modify easily the styles and the CSS properties of our web page

Add or remove CSS properties

By using the methods addClass() and removeClass() we can assign or remove a CSS class from any element

In the example, add the styles are important and color the element with id div01 when you press the button btn01, and eliminates the color style

Manipulation of CSS properties

The method css() allows us to view or modify any property of the stylesheet of an HTML element

It has the following syntax:

In case you only want to see the property, we will omit the parameter value and if we want to modify it, we'll use that parameter

In the example, we have used three paragraphs different with a style for the background color different, if you push the button with id btn03 we can see that with the css method, we have changed all the paragraphs to yellow

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Effects

Effects

JQuery allows you to, in a simple way, create effects, transitions, movements, animations, etc

Hide and Show

The method hide allows you to hide an element

To be able to re-make it visible we can use the method show

In the above example when the button is clicked with id hide has used the method to hide a parameter that indicates the speed (in milliseconds) to hide the paragraph with id part01

When you press the button with id show it has been used the show method with a parameter that indicates the speed (in milliseconds) to display the paragraph with id part01

Fading

It is similar to Toggle, since the element appears or disappears, however it does gradually

We will use this example to test the different methods of fadding

FadeIn

Allows that a hidden item appears

Supports a parameter to indicate speed (in milliseconds) or values 'slow' or 'fast'

Modify the HTML in the previous example to add this script

FadeOut

Allows an element to be hidden

Supports a parameter to indicate speed (in milliseconds) or values 'slow' or 'fast'

Modify the HTML in the previous example to add this script

FadeToggle

Allows altenar between the effects of fadeIn and fadeOut on a element

Supports a parameter to indicate speed (in milliseconds) or values 'slow' or 'fast'

Modify the HTML in the previous example to add this script

Sliding

It allows us to move items to show up or down

We will use this example to test the different methods of sliding

SlideDown

It moves down the element

Supports a parameter to indicate speed (in milliseconds) or values 'slow' or 'fast'

Modify the HTML in the previous example to add this script

SlideUp

Move element up

Supports a parameter to indicate speed (in milliseconds) or values 'slow' or 'fast'

Modify the HTML in the previous example to add this script

SlideToggle

Allows altenar between the effects slideDown and slideUp to the element

Supports a parameter to indicate speed (in milliseconds) or values 'slow' or 'fast'

Modify the HTML in the previous example to add this script

Animations

It is also possible to create custom animations with the method animate() with the following syntax:

The first parameter defines a set of CSS_Properties, enclosed between the symbols { and }, that are to be modified

The second indicates the speed(in milliseconds) or the values ‘slow’ or ‘fast’

We will use this example to test various ways of doing animations

Modify the HTML in the previous example to add this script, in which we modified a single property

Modify the HTML in the previous example to add this script, in which we modified several properties

Modify the HTML in the previous example to add this script, in which we modified several properties using relative values

We modified the HTML from the previous example to add this script, in which we modified several properties by running several consecutive animations one after another

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Ajax

AJAX

Ajax (asynchronous Javascript and XML) allows you to upload content from a web page and display it without having to recharge it

Almost any current web page uses this technology: Gmail, Google Maps, YouToube, Facebook, etc

To accomplish this, Ajax builds a layer of additional process between the website and our server

In this way, the requests to the server will be asynchronous, without interfering with the loading process or the actions of the user

While on the browser side, the user can perform actions at any time without being paralyzed waiting for a response from the server

The update of elements is performed through the layer Ajax, dynamically and continuously while the user is still using the page

Elements that make up Ajax

Now let's examine each of the different elements that make up an Ajax application

XMLHTTPRequest

The object XMLHTTPRequest is supported by all modern browsers, starting with Internet Explorer 5+, in addition to Mozilla, Firefox, Konqueror, Opera and Safari

It is supported by a wide variety of platforms, including Microsoft Windows, UNIX / Linux, and Mac OS X

The purpose of this object is to allow Javascript the formulation and sending of HTTP requests to the server

Before using the object, we must call it with its constructor and adapt it according to the peculiarities of each browser

Microsoft was the first to introduce the object, with an implementation of the same as an ActiveX

The rest of browsers have included a native version of the same though implementandolo as a Javascript object

Given that the object depends on what browser and what operating system it is able to use it, you must adapt the code to instancie correctly

In the example above shows how it would be the call of the constructor depending on the browser if using pure Javascript code

If we use the object navigator that stores information about the browser, we could do a conditional comparison according to the type of browser you just using it as a variable:

Properties of the object

  • onreadystatechange

    determines which event handler will be called when you change the property readyState the object

  • readyState

    is an integer value that reports the status of the request:

    • 0 = uninitialized
    • 1 = cárgandose
    • 2 = loaded
    • 3 = interactive
    • 4 = completed
  • responseText

    text string returned by the server that represents the data of the request

  • responseXML

    XML document returned by the server that represents the data of the request

  • status

    code HTTP status returned by the server

  • statusText

    text string returned by the server with a description of the state

Methods of the object

  • abort()

    stops the current request

  • getAllResponseHeaders()

    returns a text string containing all the headers

  • getResponseHeader(x)

    returns a text string with the value of the header x

  • open(‘method’, ‘URL’, ‘a’)

    specifies if the method of the request is GET or POST, the destination URL and if the request should be handled asynchronously (if it is true) or synchronous (if it is false)

  • send(content)

    sends the request with POST data of the form optional

  • setRequestHeader(‘x’, ‘y’)

    defines the parameters with a pair of variable (x) value (y) and is assigned to the header that is sent with the request

Ajax with jQuery

Thanks to jQuery, we can use a code more streamlined and simple that even allows us to forget the type of browser or the system thanks to the methods get(), post(), load() and ajax()

get()

This method requests data to the server with an HTTP GET request

GET is used basically for getting (retrieving) some data from the server

The GET method may return cached data

It has the following syntax:

  • URL

    is the destination address

  • callback

    is an optional parameter that represents the name of the function that will be executed in the event that the application is properly made

In the example we can see how when you press the item button will launch a GET request to the server, which in this case works with the PHP language, to the URL test.php and that contains the code that should be executed

If the request was executed successfully, execute the anonymous function that shows the user a warning with the content of the data parameter and status

post()

This method requests data to the server with an HTTP POST request

POST sends data for processing to a specified resource

The POST method never caches data, and is often used to send data along with the request

It has the following syntax:

  • URL

    is the destination address

  • data

    is an optional parameter that specifies the data that will be sent along with the application

  • callback

    is an optional parameter that represents the name of the function that will be executed in the event that the application is properly made

In the example we can see how when you press the item button will launch a POST request to the server, which in this case works with the PHP language, to the URL user.php and that contains the code about the user that should run

If the request was executed successfully, execute the anonymous function that shows the user a warning with the content of the data parameter and status

load()

This method gets content from the server and adds them to an element of our page

It has the following syntax:

  • URL

    is the destination address

  • data

    is an optional parameter that specifies the data that will be sent along with the application

  • callback

    is an optional parameter that represents the name of the function that will be executed in the event that the application is properly made

    This function must have the following mandatory parameters:

    • responseTxt

      the content of response in case of success

    • statusTxt

      is a text string with the status of the petition, you can be one of the following values:

      • abort
      • error
      • notmodified
      • parsererror
      • success
      • timeout
    • xhr

      contains the object XHTMLRequest, which provides us with additional information about the Ajax request

In the example we can see how when it is finished loading the DOM will load the content of datos.html in the element with the id div01in particular, the elements within this file that have the id p1

When you use a selector for the HTML elements that we want to load, jQuery the filter without problems, as we have seen in this example

We can also load other file types, such as for example .txtbut we have to take into account that has to be carried out by the HTTP protocol and not directly from disk (with file://)

In the event that the request fails, we would see The content will be loaded hereinstead of the loaded content

ajax()

This method performs a request asynchronous HTTP

It has the following syntax:

  • URL

    is an optional parameter that sets out the destination address, if not specified it will add it within the parameter settings as another value more

  • settings

    specifies the data that will be sent along with the application

    Can be specified default values for all Ajax requests using the method ajaxSetup()

In the example we can see that it will launch a POST request to the server, which in this case works with the PHP language, to the URL teams.php and that contains the code that should be executed

In dataType has been specified that it will receive an object of type JSON and it will use the data provided by the method called get_groups with the parameters league that picks up its value from the element with id team-league and season that picks up its value from the element with id team-season

We have included the callback hooks beforeSend,, error, dataFilter, success and complete for ilustar the order in which they are called

Only has code to errorin case of failure of the request and to successin the case that it is correct

If you are running the callback hook successis recorreran all the data received in JSON format and will be added to the element with id team-group that corresponds to an option element of a select field, this new element will be added at the end of the existing

Parameters settings

  • accepts

    assigns a dataType of type MIME, which will be sent in the header of the request

    This header informs the server what type of response will be accepted

    In the example you have assigned a MIME type to work with data in the XML format and the server will return the ‘mycustomtype‘ as we have specified

    To be able to work correctly with the new type, it is necessary to use converters to convert it correctly to the format that we want to return

  • async

    by default, all requests are sent asynchronous (set to true this is the default)

    To configure them synchronously you must asignarsele as false

    Applications cross-domain and the dataType: ‘jsonp’ do not support operations synchronous

    Keep in mind that the requests are synchronous may temporarily lock the browser, disabling any actions while the request remains active

    As of jQuery 1.8 , the use of async: false with jqXHR ($.Deferred) is deprecated; you must use the callback success, error or complete in place of the corresponding methods of the object jqXHR such as jqXHR.done()

  • beforeSend,

    it is a method of event the Ajax that is executed before the call request that can be used to modify the object jqXHR (in jQuery 1.4.x, XMLHTTPRequest) before it is sent

    Can be used to add custom headers, etc

    The objects jqXHR and settings are passed as arguments

    If it returns false, the application will be cancelled

    As of jQuery 1.5, the options are all calls, regardless of the type of application

  • cache

    if it is set to falsewill force the browser not to cache the pages requested

    Established in false will only work correctly with HEAD requests, and GET if it has been added ‘_ = {timestamp}‘ to GET parameters

    The parameter is not required for other types of requests, except in IE8 when a POST to a URL that has already been requested with GET

  • complete

    it is a method of event the Ajax that is executed after the events success and error

    This method passes two arguments: jqXHR (in jQuery 1.4.x, XMLHTTPRequest) and a text string with the status of the application (‘success‘, ‘notmodified‘, ‘nocontent‘, ‘error‘, ‘timeout‘, ‘abort‘, or ‘parsererror‘)

    As of jQuery 1.5, you can accept multiple requests and each one will turn

  • contents

    determines how jQuery will parse the response, given its content type, supports regular expressions (added in jQuery 1.5)

  • contentType

    type of content with which to send the data to the server
    The default value is ‘application/x-www-form-urlencoded; charset=UTF-8‘

    If you pass explicitly a content type to $.ajax(), will always be sent to the server (even if no data is sent)

    From jQuery 1.6 you can pass false to tell jQuery not to set any content-type header

    The W3C specification XMLHttpRequest it says that the charset should always be UTF-8; specifying another charset will not obligaráal browser to change the encoding

    For requests to cross-domain, when it is other than ‘application/x-www-form-urlencoded‘, ‘multipart/form-data‘, or ‘text/plain‘, the browser will perform checks prior to sending the request to the server

  • context

    context for all responses of the request, by default, the context is an object that represents the settings used in the call ($.ajaxSettings along with the settings you've entered with $.ajax() )

    For example, specifying a DOM element as the context will make its context to the event callback complete is:

  • converters

    method to convert the returned value to the format that we need them as answer (added in jQuery 1.5)

  • crossDomain

    is used to force a request crossDomain (such as JSONP) on the same domain, you must set the value of crossDomain to true

    This allows, for example, the redirection from the server to another domain (added in jQuery 1.5)

  • data

    data that is to be send to the server, will be converted to a query string

    Will be added to the url in GET requests

    Query the option processData to avoid this automatic process

    In the case of an array, jQuery serialize multiple values with the same key depending on the value of the setting of traditional

  • dataFilter

    method that will be used to handle the response data from the raw XMLHttpRequest

    It accepts two parameters:

    • data

      the raw data returned by the server

    • dataType
  • dataType

    type of data expected by the server

    If none is specified, jQuery will try to inferirlo based on the MIME type of the response (MIME type XML generate XML, in 1.4 JSON will generate a JavaScript object, in 1.4 script will execute the script, and any other type will be returned as a string)

    The available types (and the result passed as the first argument to your callback is accepted) are:

    • xml

      returns an XML document that can be processed via jQuery

    • html

      returns an HTML document as text without format; the labels of included script will be evaluated when inserted in the DOM

    • script

      evaluates the response as JavaScript and it is returned as plain text

      Disables caching by adding a parameter in the query string ‘_ = {timestamp}‘ to the URL unless the cache option is set as true

      In this case the POST will be converted to GET to the requests of remote-domain

    • json

      evaluates the response as JSON and returns a JavaScript object

      The json requests callback placeholder, for example ‘?callback=?‘, is made using JSONP unless the application includes jsonp: false in the configuration of the request

      The JSON data is parsed in a strict sense; any JSON with incorrect format will be rejected and will throw an error

      As of jQuery 1.9, we also reject the answers empty; the server should return a response null or {} in its place (see json.org for more information on the correction of the JSON format)

    • jsonp

      load in a block-JSON-using JSONP

      Adds ‘?callback=?‘ at the end of your URL to specify the callback of the request

      Disables caching by adding a parameter in the query string ‘_ = {timestamp}‘ to the URL unless the cache option is set as true

    • text

      string of text without format

    • multiple values separated by spaces

      as of jQuery 1.5, it is possible to convert a dataType received in the header Content-Type the necessary

      For example, if you want a string of text to be treated as XML, use ‘text xml‘

      You can also make a request JSONP, received as text, and will be interpreted by jQuery as XML: ‘jsonp text xml‘

      Similarly, the chain-shortened ‘jsonp xml‘ first, it will attempt to convert from jsonp to xml, and, failing that, convert from jsonp to text, and then text-to-xml

  • error

    event Ajax that will be called if the request fails

    As of jQuery 1.5, supports an array of methods and each one will be called per turn

    It will be called with requests cross-domain script and JSONP

    Receives the following parameters:

    • jqXHR

      (in jQuery 1.4.x, XMLHttpRequest)

    • text string

      describes the type of error that occurred

      Supports the following values:

      • null

        it is not a string, it is the literal null

      • timeout
      • error
      • abort
      • parsererror
    • errorThrown

      subject to certain exceptions, it is optional

      When an HTTP error occurs, errorThrown a party receives text of the HTTP status, such as ‘Not Found‘ or ‘Internal Server Error‘ with this parameter we can replace your options and configure it

  • global

    enables the use of several global events and Ajax
    Its default value is true

    Use false to avoid that the global events ajaxStart or ajaxStop are assets

  • headers

    additional headers sent along with the request using XMLHttpRequest, able to modify the object by changing the value X-Requested-With: XMLHttpRequest

    It is also possible to change the value with the event, Ajax beforeSend, (added in jQuery 1.5)

  • ifModified

    check the value of header Last-Modified to see if the last request was successful

    Its default value is falseignore the header

    Since jQuery 1.4, it also verifies the value of ‘etag‘ specified by the server to catch unmodified data

  • isLocal

    allows the current environment to be recognized as ‘local‘ (for example, the file system), even if jQuery does not recognize it as such by default

    The following protocols are currently recognized as local:

    • file
    • *-extension
    • widget

    If the configuration of isLocal needs to be modified, it is recommended to do it with the method $.ajaxSetup() (added in jQuery 1.5.1)

  • jsonp

    overrides the response function of the requests JSONP

    This value will be used in place of the ‘callback‘ in the query string of the url when you add ‘callback=?‘

    For example {jsonp:’onJSONPLoad’} return to the server ‘onJSONPLoad=?‘

    As of jQuery 1.5, setting jsonp to false to avoid that jQuery add the string ‘?callback‘ to the URL or attempting to use ‘=?‘ to perform the transformation

    In this case, you must explicitly set the configuration to jsonpCallback

    For example, { jsonp: false, jsonpCallback: ‘callbackName’ }

    For safety reasons, if the target receptor is not trusted, it is recommended to configure the property jsonp to false

  • jsonpCallback

    specifies the name of the function to return a request JSONP

    This value will be used instead of the random name automatically generated by jQuery

    It is recommended to let jQuery generate this unique name, since that will facilitate the management of requests and will be able to better control the callbacks and exceptions error

    It is possible to specify the return of the request when it is enabled the browser cache for GET requests

    As of jQuery 1.5, you can also use a function to set it up, in which case the value of jsonpCallback it is set with the return value of that function

  • method

    HTTP method that is utilirá in the request (for example ‘POST‘, ‘GET‘, ‘PUT‘ (added in jQuery 1.9.0)

  • mimeType

    mime type that overrides the mime type XHR (added in jQuery 1.5.1)

  • password

    password that will be used with XMLHttpRequest as a response to a request of authentication of HTTP access

  • processData

    by default, the data passed to data (anything that is not a string) will be processed and transformed to a query string, which will be set to the default content type ‘application/x-www-form-urlencoded‘

    To send a DOMDocument or other data is not processed, set it to false

  • scriptAttrs

    defines additional attributes for use in requests ‘script‘ or ‘jsonp‘

    Where:

    • key

      represents the name of the attribute

    • value

      is the value of the attribute

    When you receive this object, you will force the use of the script tag transport

    For example, can be used to declare attributes nonce, integrity or crossorigin to meet the requirements of the security policy of the content (added in jQuery 3.4.0)

  • scriptCharset

    only used with the ‘script‘ transport

    Defines the attribute charset in the script tag used in the request

    It is used when the character set on the local page is not the same as that of the remote script

    Alternatively, the attribute charset it can be defined with scriptAttrs, which will also ensure the use of transport ‘script‘

  • statusCode

    numeric codes HTTP and functions that will be called as a response to that code

    For example, when the response status is a 404, it will display a prompt to the user:

    If the request is successful, the status code of the function will take the same parameters as the return of the petition to be correct; if an error occurs (including the redirection 3xx), it will take the same parameters as the error callback (added in jQuery 1.5 )

  • success

    event Ajax call if the request is correct

    It has the following arguments:

    • data

      data returned by the server, formatted according to the parameter dataType or the callback function dataFilterif one has been defined

    • textStatus

      text string that describes the state

    • jqXHR

      (in jQuery 1.4.x, XMLHttpRequest)

    As of jQuery 1.5, supports an array of methods and each one will be called per turn

  • timeout

    sets a timeout (in milliseconds) for the request
    The value 0 means no timeout

    This will override any global timeout set with the $.ajaxSetup()

    The timeout period begins when the call is made to $.ajax

    If there are other requests in progress and the browser has no connections available, it is possible that any request to time out before it can be sent

    As of jQuery 1.4.x, the object XMLHttpRequest it will take the state to invalid if the request times out

    To access any field of the object can generate an exception

    Only in Firefox 3.0+, applications, script and JSONP are not cancelled by a timeout; the script will run even if it is received after a timeout

  • traditional

    the value will true if you want to use the traditional style of parameters serialized

  • type

    alias for method. Use type for versions of jQuery prior to 1.9.0

  • url

    string that contains the URL to which to send the request

  • username

    user name that will be used with XMLHttpRequest in response to a request of authentication of HTTP access

  • xhr

    return of the request to create the object XMLHttpRequest

    Its default value is ActiveXObject when available (IE), XMLHttpRequest otherwise

    Sobreescribalo to provide your own implementation of XMLHttpRequest or any improvement own

  • xhrFields

    defines the native object XHR (added in jQuery 1.5.1 )

    For example, can be used to define withCredentials to true for requests cross-domain, if necessary:

    In jQuery 1.5, the property withCredentials it is not native to XHR and therefore, the requests CORS (Cross-Origin Resource Sharing) that the require be ignored

    For this reason, I recommend using jQuery 1.5.1+ should you require to be used

Html, Programming language, PHP, Programming, Web Page

PHP

PHP

PHP is a development language, based on scripts oriented Web pages

It's not a markup language like HTML could be,
XML or WML

A PHP program is executed on the server and the result sent to the browser

The result will usually generate an HTML, XML, or WML page

A being a language that runs on the server is not required that the browser supports it, but for the PHP pages work, the server are housed itself must bear

PHP history

It was originally designed in language Perl, relying on a set of binary CGIRs (a program that runs on a web server) written in the language C by the Danish-Canadian programmer Rasmus Lerdorf in 1994 to show your CV and save certain data, such as the amount of traffic your website received

On June 8, 1995, it was published under the name Personal Home Page Tools after Lerdorf combined it with its own system to process forms FI (Form Interpreter) resulting in the PHP/FI

The system Personal Home Page Tools became relatively successful because others asked Rasmus to allow them to use their programs on their own pages

Two Israeli Technion programmers, Zeev Suraski and Andi Gutmans, rewrote the parser analyzer in 1997 and created the basis of PHP 3, and changed its name to PHP (Hypertext Preprocessor)

PHP3 was officially released in June 1998

In 1999, Suraski and Gutmans rewrote the PHP code and created what is now known as engine Zend. Founding Zend Technologies in Ramat Gan, Israel

In May 2000, PHP 4 was launched using the new engine Zend 1.0.

In its version 4.1, released on December 10, 2001, the variables were introduced superglobals ($_GET, $_POST, $_SESSION, etc)

In version 4.2, released on April 22, 2002, they were disabled the register_globals by default

Data received by the network were no longer inserted in the global namespace, closing possible security holes in applications

In version 4.3, released on December 27, 2002, was introduced CLI (a command line interface), and the CGI (a common interface for data entry)

In version 4.4, released on July 11, 2005, man documentation pages were added to phpize and php-config

On 13 July 2007 announced the suspension of the support and development of version 4 of PHP

However the new version 4.4.8 was released with security enhancements, which was published on 13 January 2008 and subsequently version 4.4.9, which was published on 7 August 2008

He was given support critical bugs until 9 August 2008

On 13 July 2004, PHP 5 was released, using improved engine Zend Engine 2.0 (or Zend Engine 2)

In version 5.1, released on November 24, 2005, performance improvements were added with the introduction of compiler variables for your new PHP engine

In version 5.2, released on November 2, 2006, he was added native support for JSON (JavaScript Object type)

In version 5.3, released on June 30, 2009, he added:

  • support for namespaces
  • static link runtime
  • tag jump (GOTO)
  • native Closures
  • native support for PHP files (PHAR)
  • a garbage collector for circular references
  • I improved support for Windows, sqlite3 and mysqlnd as replacement libmysql as the library for extensions that worked with MySQL database
  • including fileinfo to replace the function mime_magic to improve support for international extensions MIME and remove the deprecated ereg

In its version 5.4, released on March 1, 2012, support was added for Trait and working with abbreviated syntax arrays

the following elements being considered deprecated removed: register_globals, safe_mode, allow_call_time_pass_reference, session_register(), session_unregister() and session_is_registered()

In version 5.5, released on June 20, 2013, new generators and function loops were added empty() supports expressions

the support was also abandoned for Windows XP and Windows Server 2003

In version 5.6, released on 20 August 2014, the constants were added with scalar expressions, argument lists of variable length and the exponential by the operator **

PHP 6 development was delayed because developers decided that the approach was to treat Unicode strings was not right, and began to try alternative forms before launching this version

All improvements that were planned for PHP 6, however, were added in PHP 5.3.0 (support for namespaces, static binding at runtime, lambda functions, closures, the GOTO label) and the 5.4.0 (traits, rebinding closures)

A final version 6 was finally abandoned in favor of 7

Version 7.0, was released on November 3, 2015, performance improvements and declaration of return types were added for functions

In version 7.1, released December 01, 2016 were added the return type null, the class visibility modifier const, the type nullable, pseudo type iterators, catching multiple types of exceptions

In version 7.2, released on 30 November 2017, he was added the new return type object and integration of Libsodium as an extension of the core

In version 7.3, released on December 6 2018, a flexible syntax was added for Nowdoc and Heredoc, support for references and deconstruction of arrays with list(), support for PCRE2, function hrtime()

Version 7.4 was released on October 28 2019 and reached end of life on November 28 2022

In version 8.0, released on October 26 2020, new features were added and performance was increased

In version 8.1, released on October 25 2021, the properties were added readonly, Enums, Fiber and new syntax

In version 8.2, released on December 8 2022, the attribute was added AllowDynamicProperties and creating dynamic properties was deprecated

PHP programming

To use PHP previously we install on our server

If you also want to use a database we can use PHP in conjunction with the lightweight database manager data Mysql

Or if you want a version that takes all, also included additional server as a mail server, a file server or Tomcat for Java interpreter, we can use the free distribution of Apache Friends, XAMPP

Once installed our server and the PHP module is active and configured, we can begin our programs written in PHP on our Web pages

In the example it has been embedded PHP code in the HTML itself, but this is not the only way in which we can include it

We can see that this simple CGI script is not equal to another written in other languages ​​Perl or C

Instead of writing a complete program with all the necessary commands to generate HTML output directly write the HTML code with PHP code embedded (embedded) in the same HTML, which will output (in the example, produce text we want the body tag is displayed)

To include PHP code we use special tags beginning <?php and final ?> that will allow us to enter and exit Zend PHP interpreter

We can use 4 ways to exit and enter HTML to PHP interpreter:

  • using tags beginning <?php and final ?>

  • using abbreviated version of the beginning label <? and final ?>

    As of PHP 7 this form is deprecated

  • using the ASP version of the beginning label <% and final %>

    As of PHP 7 this form is deprecated

  • attaching to the HTML document commands as a script file

We can also directly reference a file with extension .php which we can load inside anywhere in the document HTML using the function include

However, abusing this practice can force us to copy over and over again the include function in all our HTML files

For this reason it is required to use a file index.php that generates the HTML that the browser will receive and in which only the includes that the page needs will be loaded

Separation instructions

A the same as in C or Pascal languages, statements are terminated using semicolons

The final label %> also it means the end of the sentence in the event that there is no more PHP code, so in the example are equivalent

PHP Comments

PHP supports type comments C, C++ or Shell de Unix