What is jquery based on?

jquery is implemented based on JavaScript language. jQuery is a fast and concise JavaScript framework; jQuery encapsulates commonly used functional codes (functions) in JavaScript, provides a simple JavaScript design pattern, optimizes HTML document operations, event processing, animation design and Ajax interaction, greatly simplifying the original use of JS does the job.

The operating environment of this tutorial: windows7 system, jquery3.6.1 version, Dell G3 computer.

Introduction to jQuery

jQuery is a fast and concise JavaScript framework. It is another excellent JavaScript code library (framework) after Prototype. .

jquery refers to an encapsulated JavaScript function library, a lightweight "write less, do more" JavaScript library; jquery is implemented based on the JavaScript language.

jQuery encapsulates common JavaScript function codes, provides a simple JavaScript design pattern, and optimizes HTML document operations, event processing, animation design and Ajax interaction.

The purpose of jQuery design is "write Less, Do More", which means writing less code and doing more things.

The core features of jQuery can be summarized as follows: It has a unique chain syntax and a short and clear multi-functional interface; it has an efficient and flexible CSS selector, and can extend the CSS selector; it has convenient plug-in extensions Mechanism and rich plug-ins. jQuery is compatible with various mainstream browsers, such as IE 6.0, FF 1.5, Safari 2.0, Opera 9.0, etc.

What jquery can do

jQuery provides an abstraction layer for web programming , making it compatible with any browser and greatly simplifying the work originally done with JavaScript.

In short, jQuery can complete the following tasks:

1. Quickly obtain document elements

jQuery’s selection mechanism is built on the Css selector, which provides fast The ability to query elements in DOM documents, and greatly enhances the way to obtain page elements in JavaScript.

2. Provide beautiful page dynamic effects

jQuery has a series of built-in animation effects, which can develop very beautiful web pages. Many websites use jQuery’s built-in effects, such as fade-in Dynamic special effects such as fade out and element removal.

3. Create AJAX non-refresh web pages

AJAX is the abbreviation of asynchronous JavaScript and XML. It can develop very sensitive non-refresh web pages, especially when developing server-side web pages, such as PHP websites. , need to communicate with the server back and forth. If AJAX is not used, the web page has to be refreshed every time the data is updated. However, after using AJAX special effects, the page can be partially refreshed to provide dynamic effects.

4. Provide enhancements to the JavaScript language

jQuery provides enhancements to basic JavaScript structures, such as element iteration and array processing.

5. Enhanced event handling

jQuery provides various page events, which can prevent programmers from adding too much event handling code in HTML. Most importantly, its event handling The browser eliminates various browser compatibility issues.

6. Change the content of the web page

jQuery can modify the content of the web page, such as changing the text of the web page, inserting or flipping the web page image. jQuery simplifies the way that JavaScript code needs to be processed.

13 advantages of jQuery

1. Lightweight

JQuery is very lightweight. After compression using Packer written by Dean Edwards, the size is less than 30KB, if you use the Min version and enable Gzip compression on the server side, the size is only 18KB.

2. Powerful selectors

JQuery allows developers to use almost all selectors from CSS1 to CSS3, as well as JQuery’s original advanced and complex selectors, and you can also add plug-ins to use them. It supports XPath selectors, and developers can even write their own selectors. Since JQuery supports the selector feature, developers with certain CSS experience can easily jump into learning JQuery.

3. Excellent encapsulation of DOM operations

JQuery encapsulates a large number of commonly used DOM operations, making it easy for developers to write programs related to DOM operations. JQuery easily completes various operations that were originally very complex, allowing JavaScript novices to write excellent programs.

4. Reliable event processing mechanism

JQuery's event processing mechanism absorbs the essence of the event processing function written by JavaScript expert Dean Edwards. Yes, JQuery is quite reliable when processing event bindings. . JQuery also does a very good job in terms of reserved escape routes, step-by-step and non-invasive programming ideas.

5. Perfect Ajax

JQuery encapsulates all Ajax operations into a function $.ajax(), allowing developers to concentrate on business logic when dealing with Ajax without having to worry about complexities. Issues with browser compatibility and the creation and use of XMLHttpRequest objects.

6. Do not pollute top-level variables

JQuery only creates an object named JQuery, and all its function methods are under this object. Its alias $ can also exchange control rights at any time and will never pollute other objects. This feature allows JQuery to coexist with other JavaScript libraries and be safely referenced in projects without considering later conflicts.

7. Excellent browser compatibility

As a popular JavaScript library, browser compatibility is one of the necessary conditions. JQuery can run normally under IE6.0, FF 2, Safari2. and Opera9.0. JQuery also fixes some differences between browsers, so developers don't have to build browser compatibility libraries before starting a project.

8. Chain operation method

The most distinctive thing about JQuery is its chain operation method-that is, a group of actions that occur on the same JQuery object can be directly Continuous writing does not require repeated acquisition of objects. This feature makes JQuery code extremely elegant.

9. Implicit iteration

When using JQuery to find all elements with the ".myClass" class and then hide them. No need to loop through each returned element. On the contrary, the methods in JQuery are designed to automatically operate on collections of objects instead of individual objects, which makes a large number of loop structures unnecessary, thus greatly reducing the amount of code.

10. Separation of behavior layer and structure layer

Developers can use selectors to select elements and then directly add events to the elements. This idea of ​​completely separating the behavioral layer from the structural layer allows JQuery developers and HTML or other page developers to perform their own duties, getting rid of the past development conflicts or individual development models. At the same time, post-maintenance is also very convenient. There is no need to find certain functions in the HTML code and repeatedly modify the HTML code.

11. Rich plug-in support

JQuery’s easy extensibility has attracted developers from all over the world to write JQuery extension plug-ins. There are currently more than hundreds of official plug-ins supported, and new plug-ins are constantly being interviewed.

12. Complete documentation

JQuery’s documentation is very rich. At this stage, there are many English documents and relatively few Chinese documents. Many teams who love JQuery are working hard to improve JQuery Chinese documentation, such as JQuery's Chinese API.

13. Open source

JQuery is an open source product, and anyone can freely use it and make modifications.

[Recommended learning: jQuery video tutorial, web front-end video]

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