First knowledge of jquery

about jquery

jquery is a fast, concise JavaScript framework that is a good JavaScript code base ( or JavaScript framework ) after prototype. The purpose of jquery design is "write Less,do more", which advocates writing less code and doing more things. It encapsulates the functionality code common to JavaScript, providing a simple JavaScript design pattern that optimizes HTML document manipulation, event handling, animation design, and Ajax interaction.

The core features of jquery can be summed up with a unique chain syntax and a short and clear multi-function interface, a highly efficient and flexible CSS selector, and the ability to extend the CSS selector, with convenient plug-in extension mechanisms and rich plugins. jquery is compatible with a variety of mainstream browsers such as IE 6.0+, FF 1.5+, Safari 2.0+, Opera 9.0+, and more.

Why study jquery?

　　JavaScript的功能很强大，同时也存在很多缺点，比如存在浏览器兼容处理,代码容错性差，入口函数只能有一个，假如多个话此时覆盖...

1    function () {    //Entry function 12           //  JS code 3   }4  5    function () {   //Entry function 26           //  JS code 7    }

At this point, the code below (entry function 2) overwrites the code above (entry function 1), but jquery solves these problems well.

jquery Official website: http://jquery.com jquery version: 1.x--support IE6~IE8 2.x and 3.x--no longer supported IE6~IE8 when we're using jquery, it's best to choose 1.7+ version, 1.7 The previous version is too old and is not recommended for use.

jquery Preliminary

1. Using the jquery Trilogy: The Primer and the entry function = Business logic

1 // Introducing jquery Packages 2 <script src= "Js/jquery-1.11.1.min.js" ></script>3 <script>4    //   Entry function 5    $ (function() {6        ///   Business Logic 7    }); 8 </script>

Two common ways to import functions:

A) $ (document). Ready (function () {});
b) $ (function () {});

The entry function for jquery ($ (function () {}) is executed as long as the DOM tree is loaded, does not need to wait for the loading of pictures, files, etc., and the entry function of JavaScript (window.onload = function () {} ) is to begin execution after all pictures, files, and so on in the document have been loaded.

2, $ symbol

$--is a function, the parameters are different, the function is different, but jquery and $ are completely equivalent (jquery = = $), as long as there is a place can have jquery to replace.

1 <script>2     $ ("#id")-  -   selector 3     $ ("<div> create Dom</div>")-  -   Create Dom4 5     jQuery (". Class")  --   selector 6 </script>

3. Conversion between jquery objects and Dom objects

　　Dom object:

js method gets the page element returned by the object is the DOM object, DOM object can only use the DOM object's methods or properties 　　　　 obj.innerHTML = "....";

　　jQuery对象：

　　　　 使用jQuery方法获取页面中的元素返回的对象就是jQuery对象, such as $ ("div"), $ ("#btn"), jquery objects can only use the method $ ("#btn") of the JQuery object. Show ();

The following syntax error

　　　　 $("div").innerHTML = "jquery快乐学习"; 　　　　 document.getElementById("box").show();

jquery Object Goto DOM Object

$ ("div") [index]----DOM object (recommended); Index is a number starting at 0 ("div"). Get (Index)----DOM object; Index is a number starting from 0

Dom object to jquery Object

$ (DOM object)---jquery object

First knowledge of jquery