"use strict";
 
 console.log("嚴(yán)格模式");
 console.log("在全局作用域中的this");
 console.log("this.document === document",this.document === document);
 console.log("this === window",this === window);
 this.a = 9804;
 console.log('this.a === window.a===',window.a);

 "use strict";
 
 console.log("嚴(yán)格模式");
 console.log('在全局作用域中函數(shù)中的this');
 function f1(){
 console.log(this);
 }
 
 function f2(){
 function f3(){
 console.log(this);
 }
 f3();
 }
 f1();
 f2();

 "use strict";
 
 console.log("嚴(yán)格模式");
 console.log("在對象的函數(shù)中的this");
 var o = new Object();
 o.a = 'o.a';
 o.f5 = function(){
 return this.a;
 }
 console.log(o.f5());

 "use strict";
 
 console.log("嚴(yán)格模式");
 console.log("構(gòu)造函數(shù)中的this");
 function constru(){
 this.a = 'constru.a';
 this.f2 = function(){
 console.log(this.b);
 return this.a;
 }
 }
 var o2 = new constru();
 o2.b = 'o2.b';
 console.log(o2.f2());

 "use strict";
 
 function blue_it(e){
 if(this === e.target){
 this.style.backgroundColor = "#00f";
 }
 }
 var elements = document.getElementsByTagName('*');
 for(var i=0 ; i<elements.length ; i++){
 elements[i].onclick = blue_it;
 }
 
 //這段代碼的作用是使被單擊的元素背景色變?yōu)樗{(lán)色

 <button onclick="alert((function(){'use strict'; return this})());">
 內(nèi)聯(lián)事件處理1
 </button>
 <!-- 警告窗口中的字符為undefined -->
 
 <button onclick="'use strict'; alert(this.tagName.toLowerCase());">
 內(nèi)聯(lián)事件處理2
 </button>
 <!-- 警告窗口中的字符為button -->