jq 21-94行定义变量

知识点1

(function (window,undefined) {
            
})(window);

函数自执行防止污染全局.

传入window的作用
    1. 查找变量时,window为顶层,在局部引入能节省性能?
    2.可用于压缩代码?

undefined作用
    1.某些浏览器,undefined可被修改.这是为了兼容修改的情况.

以下为21-94行,加上一些笔记.

var
    // A central reference to the root jQuery(document)
    rootjQuery,//rootjQuery = jQuery(document) 
      * 理解为document的jq对象?
    // The deferred used on DOM ready
    readyList,*老师说在dom节点时详细说

    // Support: IE9
    // For `typeof xmlNode.method` instead of `xmlNode.method !== undefined`
    core_strundefined = typeof undefined,
      *  实际上就是返回'undefined'

    // Use the correct document accordingly with window argument (sandbox)
    location = window.location,
    document = window.document,
    docElem = document.documentElement,*就是html的js对象

    // Map over jQuery in case of overwrite
    _jQuery = window.jQuery,
          *为了防jQuery全局污染冲突
    // Map over the $ in case of overwrite
    _$ = window.$,
          *为了防jQuery全局污染冲突
    // [[Class]] -> type pairs
    class2type = {},
        *用来判断类型的?
    // List of deleted data cache ids, so we can reuse them
    core_deletedIds = [],

    core_version = "2.0.3",

    // Save a reference to some core methods
    core_concat = core_deletedIds.concat,
    core_push = core_deletedIds.push,
    core_slice = core_deletedIds.slice,
    core_indexOf = core_deletedIds.indexOf,
    core_toString = class2type.toString,
    core_hasOwn = class2type.hasOwnProperty,
    core_trim = core_version.trim,
        *把数组,对象,字符串原型上的一些方法用局部变量接收,        


    // Define a local copy of jQuery
*这个就是无new构造的精髓了,另起一篇,出门左转好无new构造.
    jQuery = function( selector, context ) {
        // The jQuery object is actually just the init constructor 'enhanced'
        return new jQuery.fn.init( selector, context, rootjQuery );
    },

    // Used for matching numbers
    core_pnum = /[+-]?(?:\d*\.|)\d+(?:[eE][+-]?\d+|)/.source,

    // Used for splitting on whitespace
    core_rnotwhite = /\S+/g,

    // A simple way to check for HTML strings
    // Prioritize #id over <tag> to avoid XSS via location.hash (#9521)
    // Strict HTML recognition (#11290: must start with <)
    rquickExpr = /^(?:\s*(<[\w\W]+>)[^>]*|#([\w-]*))$/,

    // Match a standalone tag
    rsingleTag = /^<(\w+)\s*\/?>(?:<\/\1>|)$/,

    // Matches dashed string for camelizing
    rmsPrefix = /^-ms-/,
    rdashAlpha = /-([\da-z])/gi,
*上面这些正则到用的时候再回过头来看吧.
    // Used by jQuery.camelCase as callback to replace()
    fcamelCase = function( all, letter ) {
*这个all是用来干什么的?看不懂.
*http://www.cnblogs.com/kuangliu/p/4724424.html 
*这又是个大神
*这个all是用来和replace配合的.比如str.repalce(reg,fcamelCase);
*不过还是没完全理解.
        return letter.toUpperCase();
    },

    // The ready event handler and self cleanup method
    completed = function() {
        document.removeEventListener( "DOMContentLoaded", completed, false );
        window.removeEventListener( "load", completed, false );
        jQuery.ready();
    };

最后编辑于：2018.09.11 20:48:14

jq 21-94行 定义变量

jq 21-94行定义变量