However, no matter how close it is, there will always be time to wait for the data to be loaded through the back and forth between the client and the server. Therefore, most websites use a Gif dynamic icon or words such as 'Loading...' to inform users that the data is still loading. But sometimes this problem will be very tedious and troublesome, either display this 'Loading' before the ajax request, and then hide it after the ajax is successful, or write it in the global event jQuery.ajaxStart() of jquery's ajax and jQuery. ajaxStop() to control the ajax state of the entire page. The former method is too trivial to use. You have to write this 'Loading' for every request, and you need to hide it regardless of whether the request succeeds or fails. The latter is global, that is, the request status of the entire page. Sometimes it cannot meet the requirement of displaying the loading status locally.
In order to solve these problems, I developed a jQuery plug-in called: Ajax Request Status Manager. Using this plug-in can make loading less troublesome. You can use this plug-in to add and write all requests before triggering an ajax request. All you have to do is execute the .request() method in the user interaction event. You can set all requests on a page to display loading independently, or you can set it to display globally (only one loading is displayed). The following is the specific usage of the plug-in:
Customize the css style of loading:
.state-loading { background: #fff url(images/icon-ajax-loader.gif) ... }
Quote the latest version of jquery file:
Note: This plug-in is only tested in jquery1.4.4 and later versions.
Quote the Ajax request status manager plug-in file:
In the ready event of jquery Execute the .install() method in:
$.loader.install( className, isGlobal );
Parameter description:
className: string, indicating your customized loading class name, such as the above State-loading defined by css.
isGlobal: boolean, defines whether loading is displayed globally or independently. The default value is true. This parameter can be omitted.
Add the required ajax request parameters and the callback method after success:
$.loader( key ).add( modules, settings , callback );
Parameter description:
Key: string, use this key to create or obtain the loader of the specified module. Of course, the same key can execute the add() method multiple times to add different modules, but settings and callbacks are shared for this key, so settings and callbacks added later will overwrite the previous ones.
modules: jquery object. The same request in a page can process data from multiple modules. Therefore, if the install() method was set to false before, when executing the ajax request, add it to this loader. All modules will display the loading status.
Settings: map, jquery's ajax settings parameter, but do not set the ajax event. This will override the callback method in the plug-in. The default request type is GET.
callback: function, the callback function after success. It has a parameter data, which defaults to an object returned by json type.
The add() method returns a string array prefixed by 'module'. For example, if you add 3 elements, the result is ['module1', 'module2', 'module3']. You can delete the loading of one of the specified modules through the returned array, or you can not specify it, that is, delete them all, of course, if you need to do this.
remove() method deletes the specified module:
$.loader( key ).remove( moduleId );
Parameter description:
moduleId: string or array, specified as If it is a string, one of the modules will be deleted. If it is specified as an array, the modules will be deleted in batches. If no parameters are specified, all modules will be deleted.
Example
Add 2 modules to the loader named userinfo:
var id1 = $.loader( 'userinfo' ).add(
$( '#userinfo, #top-userinfo' ),
{ url: 'server/ userinfo.php' },
function( data ) {
updateContent( $( '#userinfo, #topsection, #footer-userinfo' ), data );
}
);
Add another module to the userinfo loader:
var id2 = $.loader( 'userinfo' ).add( $('#footer-userinfo') );
var idList = id1.concat( id2 );
// result: [ 'module1', 'module2', 'module3' ]
Delete the loading of the second module, that is, '#top-userinfo':
var ret = $.loader( 'userinfo' ).remove( idList[1] );
// result: true, modules: [ 'module1', 'module3' ]
Executed in interactive events. request() method:
$.loader( key ).request();
]
Of course, you can also abandon the ajax settings and callback added before, and write $.ajax yourself in the interactive event or $.get etc. Then call $.loader( key ).show() before the request and $.loader( key ).hide() within the callback function. This also allows you to flexibly control the loading status.
Example
$( '#getUserInfo ' ).bind( 'click', function() {
$.loader( 'userinfo' ).request();
});
You can also rewrite it from scratch Request:
$( '#getUserInfo' ).bind( 'click', function() {
$.loader( 'userinfo' ).show();
$.get( 'server/userinfo.php', function( data ) {
$.loader ( 'userinfo' ).hide();
updateContent( $( '#userinfo, #topsection, #footer-userinfo' ), data );
})
});
Note: When a request is triggered repeatedly, the manager will execute abor() to prevent the previously unfinished request and reissue a new request. However, if you output error information through jquery's ajaxError event on the page, it will This information is also considered incorrect, so you need to filter it yourself if necessary.
Example
//Output error log
$( 'body' ).bind( 'ajaxError', function( event, xhr, setting, thrownError ) {
// Filter out abort error message
if ( xhr.status === 0 || xhr.readyState === 0 || thrownError '' );
});
The plug-in is simple and easy to use, and the code logic is not very complicated. However, my ability and technical level are limited. If I encounter If you have any questions or bugs, please tell me via email: nicolas-zhao@hotmail.com. Thanks for coming!
Ajax request status manager
.

JavaScript is widely used in websites, mobile applications, desktop applications and server-side programming. 1) In website development, JavaScript operates DOM together with HTML and CSS to achieve dynamic effects and supports frameworks such as jQuery and React. 2) Through ReactNative and Ionic, JavaScript is used to develop cross-platform mobile applications. 3) The Electron framework enables JavaScript to build desktop applications. 4) Node.js allows JavaScript to run on the server side and supports high concurrent requests.

Python is more suitable for data science and automation, while JavaScript is more suitable for front-end and full-stack development. 1. Python performs well in data science and machine learning, using libraries such as NumPy and Pandas for data processing and modeling. 2. Python is concise and efficient in automation and scripting. 3. JavaScript is indispensable in front-end development and is used to build dynamic web pages and single-page applications. 4. JavaScript plays a role in back-end development through Node.js and supports full-stack development.

C and C play a vital role in the JavaScript engine, mainly used to implement interpreters and JIT compilers. 1) C is used to parse JavaScript source code and generate an abstract syntax tree. 2) C is responsible for generating and executing bytecode. 3) C implements the JIT compiler, optimizes and compiles hot-spot code at runtime, and significantly improves the execution efficiency of JavaScript.

JavaScript's application in the real world includes front-end and back-end development. 1) Display front-end applications by building a TODO list application, involving DOM operations and event processing. 2) Build RESTfulAPI through Node.js and Express to demonstrate back-end applications.

The main uses of JavaScript in web development include client interaction, form verification and asynchronous communication. 1) Dynamic content update and user interaction through DOM operations; 2) Client verification is carried out before the user submits data to improve the user experience; 3) Refreshless communication with the server is achieved through AJAX technology.

Understanding how JavaScript engine works internally is important to developers because it helps write more efficient code and understand performance bottlenecks and optimization strategies. 1) The engine's workflow includes three stages: parsing, compiling and execution; 2) During the execution process, the engine will perform dynamic optimization, such as inline cache and hidden classes; 3) Best practices include avoiding global variables, optimizing loops, using const and lets, and avoiding excessive use of closures.

Python is more suitable for beginners, with a smooth learning curve and concise syntax; JavaScript is suitable for front-end development, with a steep learning curve and flexible syntax. 1. Python syntax is intuitive and suitable for data science and back-end development. 2. JavaScript is flexible and widely used in front-end and server-side programming.

Python and JavaScript have their own advantages and disadvantages in terms of community, libraries and resources. 1) The Python community is friendly and suitable for beginners, but the front-end development resources are not as rich as JavaScript. 2) Python is powerful in data science and machine learning libraries, while JavaScript is better in front-end development libraries and frameworks. 3) Both have rich learning resources, but Python is suitable for starting with official documents, while JavaScript is better with MDNWebDocs. The choice should be based on project needs and personal interests.


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