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console.log(this.document === document); //true
//å¨webæµè§å¨ä¸ï¼window对象å³æ¯å
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console.log(this === window); // true
this.a=37;
console.logn(window.a); //37
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function f2(){
"use strict";//使ç¨ä¸¥æ ¼æ¨¡å¼
return this;
}
f2() === undefined;
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