There are several types of jquery asynchronous requests

There are 4 types of jquery asynchronous requests: 1. Ajax request, the syntax is "$.ajax({name:value,...})"; 2. Get request, the syntax is "$.get(url, pass Parameters, callback function, type)"; 3. getJSON request, supports cross-domain calls; 4. post request.

The operating environment of this tutorial: windows10 system, jquery3.2.1 version, Dell G3 computer.

There are several types of jquery asynchronous requests

The first Ajax request:

$.ajax(): is the core method.

$.ajax() method is a powerful and direct way to create Ajax requests. It is passed an options object as a parameter, and the properties of this options object configure all the instructions required to complete the request.

$.ajax() provides success and failure callback functions.

Syntax:

$.ajax({name:value, name:value, … })

Save data to the server, display information when successful

$.ajax({
   type: "POST",
   url: "some.php",
   data: "name=John&location=Boston",
   success: function(msg){
     alert( "Data Saved: " + msg );
   }
});

Comments:

type: (default: "GET"), request Method ("POST" or "GET") Other request methods are only supported by some browsers.

url: (Default current page address) The address to send the request.

data: stored data.

success: Called after the request, the returned data and the string containing the success code are transferred.

Function() needs to store the global variables declared on the controller side

The second $.get() request:

Syntax:

$.get(url address, parameter passed by param, callback function, return value type)

Note:

Parameters: optional;

Return value type: The type can be automatically matched according to the data (generally can be omitted)

(via remote HTTP GET request loads information. This is a simple GET request function to replace the complex $.ajax. The callback function can be called when the request is successful. If you need to execute the function when an error occurs, use $.ajax.)

Description:

Display test.php return value (HTML or XML, depending on the return value).

jQuery code:

$.get("test.php", function(data){
          alert("Data Loaded: " + data);
});

Third $.post() request:

Syntax:

$.post (url address, parameters passed by param, callback function, return value type)

Note:

Parameters: Optional;

Return value type: The type can be automatically matched according to the data (generally can be omitted)

(Load information through remote HTTP POST request)

Description:

Output results from the requested page test.php (HTML or XML, depending on what is returned):

jQuery Code:

$.post("test.php", function(data){
          alert("Data Loaded: " + data);
          });

The fourth $.getJSON() request:

##$.getJSON() is specifically Set up for ajax to obtain json data, and supports cross-domain calls.

Note: JSON is an ideal data transmission format. It can be well integrated with JavaScript or other host languages ​​and can be used directly by JS.

Syntax:

$.getJSON(url address, parameter passed by param (optional), callback function)

(Load JSON data through HTTP GET request)

jQuery Code:

$.getJSON("http://api.flickr.com/services/feeds/photos_public.gne?tags=cat&tagmode=any&format
=json&jsoncallback=?", function(data){
  $.each(data.items, function(i,item){
    $("<img / alt="There are several types of jquery asynchronous requests" >").attr("src", item.media.m).appendTo("#images");
    if ( i == 3 ) return false;
  });
});

Note: The

$.getJSON() request is different from the first three. What is returned in the controller is not Content but It is a code in JSon format

Related video tutorial recommendations:

jQuery video tutorial

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