What is the difference between jQuery JavaScript ajax

jQuery JavaScript ajax difference: 1. javaScript is widely used as a scripting language for client-side web development and is often used to add dynamic functions to HTML web pages; 2. AJAX is a web development technology for creating interactive web applications; 3. jQuery Conveniently provide AJAX interaction for websites.

jQuery JavaScript ajax difference:

1, JavaScript

The abbreviation of javaScript is JS, a scripting language widely used in client-side web development. It is often used to add dynamic functions to HTML web pages (the programs written by it can be embedded into HTML or XML pages and interpreted directly in the browser) implement).

Components:

Core (ECMAScript), Document Object Model (DOM), Browser Object Model (BOM)

Description:

• Javascript is a new programming language born to meet the needs of dynamic web page production. It is now more and more widely used in Internet web page production.

• The emergence of Javascript enables a real-time, dynamic, and interactive relationship between web pages and users, making web pages contain more active elements and more exciting content .

• Javascript is short and concise, and is executed on the client machine, which greatly improves the browsing speed and interactive capabilities of web pages. At the same time, it is a simple programming language specifically tailored for making Web pages.

2. Ajax

AJAX is "Asynchronous JavaScript and XML" (asynchronous JavaScript and XML). AJAX is not an abbreviation, but an abbreviation. A term coined by Jesse James Gaiiett to refer to a web development technology for creating interactive web applications.

Composition:

• ## Representation based on XHTML and CSS standards;

• Use Document Object Model for dynamic display and interaction;

• Use XML and XSLT for data interaction and operation;

• Use XML HttpRequest for asynchronous communication with the server;

• Use JavaScript to bind everything.

Description:

• Ajax is a combination of Java technology, XML, JavaScript and other programming technologies that allows developers to build Web based on Java technology Apply and break management using page reloads.

• Ajax technology uses asynchronous HTTP requests to transfer data between the Browser and the Web Server, so that the Browser only updates part of the web page content without reloading the entire web page.

• Ajax is a Web application development method that uses client-side scripts to exchange data with the Web server. In this way, the Web page can be dynamically updated without interrupting the interaction process and re-editing it. Using Ajax, users can create direct, highly available, richer, and more dynamic web user interfaces that are close to native desktop applications

3, jQuery

jQuery is a fast, concise javaScript library that enables users to more easily process HTML documents and events, achieve animation effects, and easily provide AJAX interaction for websites.

Features:

jQuery is a very popular JavaScript framework. It uses selectors similar to CSS to easily operate HTML elements. It has good scalability and has many plugin.

Description:

• For programmers, simplifying javascript and ajax programming can free programmers from designing and writing complex JS applications, and focus on Focus on functional requirements rather than implementation details, thereby increasing the speed of project development.

• For users, it improves the visual effect of the page, enhances the interactivity with the page, and experiences more gorgeous web page materials.

• The javaScript framework is actually a series of tools and functions.

The relationship between the two and the three

I will use a map to illustrate the relationship between the three:

Explanation:

JavaScript is a scripting language used for Web client development. Ajax is a new technology based on JS language that mainly combines JS, CSS, and XML technologies. It is used to create interactive web applications. Web development technology. jQuery is a JS framework. It is a JS library developed based on the JS language and Ajax technology. It encapsulates the functions of JS and Ajax and provides functional interfaces, which greatly simplifies the operations of Ajax and JS.

jQuery is often used in projects, let’s talk about it in detail.

jQuery can greatly simplify the writing of JavaScript programs

To use jQuery, you must first add a reference to the jQuery library at the beginning of the HTML code, for example:

<script language="javascript" src="/js/jquery.min.js"></script>   //引用

The library file can be placed locally, or you can directly use the CDN of a well-known company (CDN loading The advantage of jquery) is that CDNs of these large companies are relatively popular. Before users visit your website, they are likely to have cached it in the browser when visiting other websites, so it can speed up the opening of the website. Another benefit is obvious, saving website traffic bandwidth.

Provided by Google

http://ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js

jQuery official

http://code.jquery.com/jquery-1.6.min.js

The difference between the specific writing method of jQuery code and the native Javascript writing method when performing common operations is as follows:

1 Positioning elements

JS

document.getElementById("abc")

jQuery

$("# abc") Positioning by id

$(".abc") Positioning by class

$("div") Positioning by tag

It should be noted that the JS returns The result is this element, and the result returned by jQuery is a JS object. The following example assumes that element abc has been positioned.

2 Change the content of the element

JS

abc.innerHTML = "test"; //Useful in current projects

jQuery

abc.html("test");

3 Show hidden elements

JS

abc.style .display = "none";                                                                               using  

abc.style.display = "block";    

jQuery  

abc.hide();

abc.show();

abc.toggle(); //Switch between showing and hiding,

4 Get focus

JS and jQuery are the same, both are abc.focus();

5 Assign values ​​to the form

JS

abc .value = "test";

jQuery

abc.val("test");

6 Get the value of the form

JS

alert(abc.value);

jQuery

alert(abc.val());

7 Set elements Not available

JS

abc.disabled = true;

jQuery

abc.attr("disabled", true);

8 Modify element style

JS

abc.style.fontSize=size;

jQuery

abc. css('font-size', 20);

JS

abc.className="test";

JQuery

abc.removeClass() ;

abc.addClass("test");

9 Determine whether the check box is selected

jQuery

if( abc.attr("checked") == "checked")

Note: It is said on the Internet that .attr("checked") == true cannot actually be used. The above test can be used

Related free learning recommendations: JavaScript (video)

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