Prototype 源码 1

var Prototype = {
    Version: "1.7.3",

    Browser: (
      function () {
        var ua = navigator.userAgent;
        var isOpera = (Object.prototype.toString.call(window.opera)) == "[object Opera]";
        return {
          IE: (!(!(window.attachEvent))) && (!isOpera),

          Opera: isOpera,

          WebKit: (ua.indexOf("AppleWebKit/")) > (-1),

          Gecko: ((ua.indexOf("Gecko")) > (-1)) && ((ua.indexOf("KHTML")) === (-1)),

          MobileSafari: /Apple.*Mobile/.test(ua)
        };
      }
    )(),

    BrowserFeatures: {
      XPath: !(!(document.evaluate)),

      SelectorsAPI: !(!(document.querySelector)),

      ElementExtensions: (
        function () {
          var constructor = (window.Element) || (window.HTMLElement);
          return !(!(constructor && (constructor.prototype)));
        }
      )(),

      SpecificElementExtensions: (
        function () {
          if ((typeof (window.HTMLDivElement)) !== "undefined")
            return true;

          var div = document.createElement("div"),

            form = document.createElement("form"),

            isSupported = false;
          if ((div["__proto__"]) && ((div["__proto__"]) !== (form["__proto__"]))) {
            isSupported = true;
          }

          div = form = null;
          return isSupported;
        }
      )()
    },

    ScriptFragment: "<script[^>]*>([\\S\\s]*?)</script\\s*>",

    JSONFilter: /^\/\*-secure-([\s\S]*)\*\/\s*$/,

    emptyFunction: function () {},

    K: function (x) {
      return x;
    }
}　　

## 知识点更新：

 

### navigator 包含浏览器的信息。http://www.w3school.com.cn/jsref/dom_obj_navigator.asp

常见用法：navigator.userAgent 返回userAgent头部，

例如 "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.100 Safari/537.36"

使用navigator.userAgent判断浏览器类型： http://blog.csdn.net/tivonalh/article/details/55511143

 

### 2.Object.prototype 属性

Object.prototype.toString() 返回一个表示该对象的字符串，是用来判断对象类型的。

这里不得不提typeof，typeof只能区分基本类型，Number，String，Boolean，Undefined，Object，

如果要区分对象，数组，函数，typeof就不再适用，此时Object.prototype.toString()就派上用场。

http://blog.csdn.net/icanlove/article/details/43702879

https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Object/prototype

 

### 3.call apply bind 用法

http://www.cnblogs.com/coco1s/p/4833199.html

 

### 4.attachEvent

attachEvent——兼容：IE7、IE8；不兼容firefox、chrome、IE9、IE10、IE11、safari、opera

addEventListener——兼容：firefox、chrome、IE、safari、opera；不兼容IE7、IE8

https://developer.mozilla.org/zh-CN/docs/Web/API/EventTarget/addEventListener

 

### 5.document.querySelector

https://developer.mozilla.org/zh-CN/docs/Web/API/Document/querySelector

### HTMLElement 和 Element
window.HTMLElement 继承 Element，代表任何HTML元素