What are the uses of ajax? Detailed explanation of the specific usage of ajax

This article mainly explains to you the usage details of ajax, and there are examples to prove it, so that everyone can understand the content of the article more quickly. Now let’s look at this article together

Syntax: $.ajax([settings]);

##

$.ajax({  
    type: "POST",  
    url: "UserLogincheck",  
    data: {username:$("#username").val(), password:$("#password").val(),verify:$("#verify").val()},  
    dataType: "json",  
    success: function(data){  
        if(data==1){  
            // 用户名或密码错误  
            alert("用户名或密码错误");  
        }  
        else if(data==2){  
            alert("验证码错误");  
            // 验证码错误  
        }  
        else if(data==0){  
            window.location.href="index";  
        }  
        //跳转页面  
    },  
    error:function(XMLHttpRequest, textStatus, errorThrown){//请求失败时调用此函数  
        console.log(XMLHttpRequest.status);  
        console.log(XMLHttpRequest.readyState);  
        console.log(textStatus);                              
    }  
});

php as the background processing process

##

public function UserLogincheck(){//用户登陆验证(用户名和邮箱均可登陆)  
                $very = new \Think\Verify();  
                if($very->check($_POST['verify'])){//验证码正确  
                 $user_admin = I('post.username');  
                 $judge = " (user_name = '$user_admin' or user_email = '$user_admin' )";  
                 $user_del_status = $this->user->where($judge)->getField('user_del');  
                   if($user_del_status == 0){//用户未被注销  
                       $user_password = I('post.password');  
                       $judge .= "and user_password = '$user_password'";  
                       $res = $this->user->where($judge)->find();  
                       if($res){//记录用户登陆状态  
                         $_SESSION['ADMIN_user_id'] = $this->user->where($judge)->getField('user_id');  
                         $_SESSION['ADMIN_user_name'] = $data['user_name'];  
                         $this->ajaxReturn(0);//登陆成功  
                       }  
                       $this->ajaxReturn(1);//用户名或密码错误  
                   }  
                   else  
                     $this->ajaxReturn(8);//用户信息被注销  
                }  
                else  
                  $this->ajaxReturn(2);//验证码错误  
       }

Detailed explanation of ajax parameters:

##data

Type: String

Data sent to the server. Will be automatically converted to request string format. Appended to the URL in GET requests. See the processData option description to disable this automatic conversion. Must be in Key/Value format. 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'.

(If you want to see more, go to the PHP Chinese website

AJAX Development Manual

column to learn) dataFilter

Type: Function

Function for preprocessing the original data returned by Ajax. Provide two parameters, data and type: data is the original data returned by Ajax, and type is the dataType parameter provided when calling jQuery.ajax. The value returned by the function will be further processed by jQuery.

dataType

Type: String

The expected data type returned by the server. If not specified, jQuery will automatically make intelligent judgments based on the MIME information of the HTTP package. For example, the XML MIME type is recognized as XML. In 1.4, JSON will generate a JavaScript object, and script will execute the script. The data returned by the server will then be parsed based on this value and passed to the callback function. Available values:

"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 automatically cached. Unless the "cache" parameter is set. Note: When making remote requests (not under the same domain), all POST requests will be converted into GET requests. (Because the DOM script tag will be used to load)

"json": Returns JSON data.

"jsonp": JSONP format. When calling a function using JSONP form, such as "myurl?callback=?" jQuery will automatically replace ? with the correct function name to execute the callback function.

"text": Returns a plain text string

error

Type: Function

Default value: Automatic judgment (xml or html). This function is called when the request fails.

has the following three parameters: XMLHttpRequest object, error message, (optional) captured exception object.

If an error occurs, the error message (the second parameter) may be "timeout", "error", "notmodified" and "parsererror" in addition to null.

This is an Ajax event.

global

Type: Boolean

Whether to trigger the global AJAX event. Default value: true. Setting to false will not trigger global AJAX events such as ajaxStart or ajaxStop which can be used to control different Ajax events.

ifModified

Type: Boolean

Get new data only when the server data changes. Default value: false. Use HTTP packet Last-Modified header information to determine. As of jQuery 1.4, it also checks the server-specified 'etag' to make sure the data has not been modified.

jsonp

Type: String

Override the name of the callback function in a jsonp request. This value is used to replace the "callback" part of the URL parameter in a GET or POST request such as {jsonp:'onJsonPLoad'} which will cause "onJsonPLoad=?" to be passed to the server.

jsonpCallback

Type: String

Specify a callback function name for the jsonp request. This value will be used instead of the random function name automatically generated by jQuery. This is mainly used to allow jQuery to generate unique function names so that it is easier to manage requests and provide callback functions and error handling. You can also specify this callback function name when you want the browser to cache GET requests.

password

Type: String

Password used to respond to HTTP access authentication requests

processData

Type: Boolean

Default value: true. By default, the data passed in through the data option, if it is an object (technically speaking, as long as it is not a string), will be processed and converted into a query string to match the default content type "application/x-www-form-urlencoded" ". Set to false if you want to send DOM tree information or other information that you don't want to convert.

scriptCharset

Type: String

Only when the dataType is "jsonp" or "script" when requesting, and the type is "GET" Used to force modification of charset. Usually only used when the local and remote content encodings are different.

success

Type: Function

The callback function after the request is successful.

Parameters: Data returned by the server and processed according to the dataType parameter; a string describing the status.

This is an Ajax event.

traditional

Type: Boolean

Set to true if you want to serialize data in the traditional way. Please refer to the jQuery.param method under the Tools category.

timeout

Type: Number

Set the request timeout (milliseconds). This setting overrides the global setting.

type

Type: String

Default value: "GET"). Request method ("POST" or "GET"), default is "GET". Note: Other HTTP request methods such as PUT and DELETE can also be used, but are only supported by some browsers.

url

Type: String

Default value: Current page address. The address to send the request to.

username

Type: String

Username used to respond to HTTP access authentication requests.

xhr

Type: Function

Needs to return an XMLHttpRequest object. The default is ActiveXObject under IE and XMLHttpRequest otherwise. Used to override or provide an enhanced XMLHttpRequest object. This parameter was not available before jQuery 1.3.

This article ends here (if you want to see more, go to the PHP Chinese website AJAX User Manual column to learn). If you have any questions, you can leave a message below.

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