Detailed explanation of Ajax get, post and other methods in jQuery_jquery

load() method is usually used to obtain static data files from the web server, but this does not reflect the full value of ajax.

In the project, if you need to pass some parameters to the page on the server, you can use the $.get() or $.post() method (or the $.ajax() method)

$.get() method Uses GET method to make asynchronous requests. The structure is: $.get(url [, data] [, callback] [, type])

$.get() method parameters are explained as follows:

Parameter name	Type	Description
url	String	The URL address of the requested HTML page
data(optional)	Object	The key/value data sent to the server will be appended to the request URL as QueryString
callback(optional)	Function	The callback function is called when loading is successful (this method is only called when the return status of Response is success) and the request result and status are automatically passed to this method
type(optional)	String	The format of content returned by the server, including xml, html, script, json, text and _default

$.post() method.

The structure and usage of the $.post() and $.get() methods are the same, but there are still the following differences between them:

The GET request will pass the parameters after the URL, while the POST request will be sent to the web server as the entity content of the HTTP message.
The GET method has a size limit on the data transmitted (usually no more than 2KB), while the amount of data transmitted using the POST method is much larger than the GET method (theoretically not limited)
The data requested by GET method will be cached by the browser, so others can read the data from the browser's history, such as account number and password. In some cases, the GET method will cause serious security problems, while the POST method can relatively avoid these problems
The data transferred by GET method and POST method are obtained differently on the server side.

$.getScript(): jQuery provides this method to load js files directly, which is as simple and convenient as loading an HTML fragment, and does not require processing of JavaScript files, JavaScript files will be executed automatically.

The jQuery code is as follows:

Copy code The code is as follows:

$(function () {
           $("#send").click(function () {
               $.getScript("test.js");
        });
})

Like other ajax methods, the $.getScript() method also has a callback function, which will run after the JavaScript file is loaded successfully.

For example: If you want to load the jQuery official color animation plug-in (jquery.color.js), and bind the color change animation to the element after success:

Copy code The code is as follows:

run

$.getJson(): This method is used to load JSON files, and its usage is the same as $.getScript().

Copy code The code is as follows:

   
   
   
   

   

已有评论：

';
                })
                $('#resText').html(html);
            })
        })
    })

test.json文件为：

复制代码 代码如下:

[
  {
    "username": "张三",
    "content": "沙发."
  },
  {
    "username": "李四",
    "content": "板凳."
  },
  {
    "username": "王五",
    "content": "地板."
  }
]

 
使用JSONP形式的回调函数来加载其他网站的JSON数据。例如：

复制代码 代码如下:

   
   
   
   

   

Note:

jQuery will automatically replace the callback function in the URL, such as the last "?" in "url?callback=?", with the correct function name to execute the callback function.
JSONP (JSON with Padding) is an unofficial protocol that allows integrating Script tags on the server side and returning them to the client, achieving cross-domain access through JavaScript Callback. Since JSON is just plain text with a simple bracket structure, many channels can exchange JSON messages. Due to the restrictions of the same origin policy, developers cannot use XMLHttpRequest when communicating with external servers. JSONP is a method that can bypass the same origin policy, that is, by using a combination of JSON and <script> tags to directly return executable JavaScript function calls or JavaScript objects from the server side. At present, JSONP has become the first choice for cross-domain web applications of major companies. <br /> The $.ajax() method is jQuery’s lowest-level ajax implementation. Its structure is:</script>

$.ajax(options). This method has only one parameter, but this object contains the request settings and callback functions required by the $.ajax() method. The parameters exist in the form of key/value. All Parameters are optional,

The commonly used parameter list is:

Parameter name	Type	Description
url	String	(Default is the current page address) The address to send the request
type	String	The request method (post or get) defaults to get. Note that other HTTP request methods such as PUT and DELETE can also be used, but only some browsers support
timeout	Number	Set request timeout (milliseconds).This setting will override the global setting of the $.ajaxSetup() method
data	Object or String	Data sent to the server. If it is not a string, it will be automatically converted to string format. The GET request will be appended to the url. To prevent this automatic conversion, check the processData option. The object must be in key/value format, for example {foo1:"bar1", foo2:"bar2"} is converted to &foo1=bar1&foo2=bar2. If it is an array, jQuery will automatically assign the same name to different values. For example, {foo:["bar1", "bar2"]} is converted to &foo=bar1&foo=bar2
dataType	String	The data type expected to be returned by the server. If not specified, jQuery will automatically return responseXML or responseText based on the HTTP packet MIME information and pass it as a callback function parameter. The available types are as follows. xml: Returns an XML document that can be processed with jQuery html: Returns plain text HTML information; the included script tag will be executed when inserted into the DOM script: Returns plain text JavaScript code. Results are not cached automatically. Unless cache parameters are set. Note that when making remote requests (not under the same domain), all POST requests will be converted into GET requests. json: Return JSON data jsonp: JSONP format. When calling a function using JSONP format, such as myurl?callback=?, jQuery will automatically replace the last "?" with the correct function name to execute the callback function. text: Returns a plain text string
beforeSend	Function	You can modify the functions of the XMLHttpRequest object before sending the request, such as adding custom HTTP headers. If false is returned in beforeSend, this Ajax request can be canceled. The XMLHttpRequest object is the only parameter. function(XMLHttpRequest) { 　this;//The options parameter passed when calling this Ajax request }
complete	Function	Callback function called after the request is completed (called when the request succeeds or fails) Parameters: XMLHttpRequest object and a string describing the successful request type. function(XMLHttpRequest, textStatue){ 　this;//The options parameter passed when calling this Ajax request }
success	Function	The callback function called after a successful request has two parameters. (1) Data returned by the server and processed according to the dataType parameter (2) String describing status function(data, textStatus) { //data may be xmlDoc, jsonObj, html, text, etc. 　this;//The options parameter passed when calling this Ajax request }
error	Function	Function called when the request fails. This function has three parameters, namely XMLHttpRequest object, error message, and captured error object (optional). The Ajax event function is as follows: function(XMLHttpRequest, textStatus, errorThrown) { //Usually only one of textStatus and errorThrown contains information 　this;//The options parameter passed when calling this Ajax request }
global	Boolean	Defaults to true. Indicates whether to trigger global Ajax events. Setting to false will not trigger global Ajax events, AjaxStart or AjaxStop can be used to control various Ajax events