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this ʼÖÕÖ¸Ïòµ÷ÓÃËüµÄ¶ÔÏó ,¶¼Ã»ÓжÔÏóµ÷ÓÃʱ¾ÍÖ¸Ïòwindow
ÁíÍâ¾ÍÊÇthisÒ»°ã¶¼ÊÇÔÚfunctionÖÐ,µ±²»ÔÚfunctionÖеÄʱºò  Ò»¶¨ÊÇÖ¸ÏòwindowµÄ.
var a ='a';
alert(this.a); //³öÀ´µÄÊÇa
alert(this.b); //undefined ÒòΪ»¹Ã»¶¨Òå
var b= 'b';
alert(this.b); //³öÀ´µÄÊÇb ËùÓеÄÈ«¾Ö±äÁ¿¶¼ÊÇwindowµÄÊôÐÔ
µ±ÔÚfunctionÖеÄʱºò,Èç¹ûûÓжÔÏóµ÷ÓÃËü»¹ÊÇÖ¸ÏòwindowµÄ
var a ='a';
function test(){
alert(this.a)
}
test();
ÓÐÈ˾õµÃthisÊǸù¾ÝÉÏÏÂÎÄÀ´È·¶¨µÄ,·´ÕýÎÒ²»Ã÷°×ÕâÊÇʲôÒâ˼  Ö»Òª×¥×¡Ò»µã ÓÐûÓжÔÏóµ÷ÓÃËü¾ÍºÃÁË,²»¹ÜÕâ¸öthisÒþ²ØµÄÓÐÉî
 var a ='a';
function test(){
(function(){
(function(){
(function(){
alert(this.a); //Õâ¸öthisÒþ²ØµÄ¹»ÉîÁ衃 µ«ÊÇûÓжÔÏóµ÷Óà »¹ÊÇÖ¸Ïòwindow
})();
})();
})()
}
test();
ÔÚfunctionÖР µ±ÓжÔÏóµ÷ÓÃÕâ¸öfunctionµÄʱºò  this¾ÍÖ¸ÏòÕâ¸ö¶ÔÏóÁË......
 var vv = "wo bu shi vv";
function text(){
alert(this.vv)
};
var obj = {
vv : "vv",
say :text
};
text(); //¿ÉÒÔ¿´µ½ ûÓжÔÏóµ÷Óà ָÏòµÄÊÇwindow
obj.say();//sayÒýÓõÄtext ÓжÔÏóµ÷ÓÃ(obj) thisÖ¸ÏòµÄÊÇobj
ÔÚjsÖÐÓÐÒ»¸öÉñÆæµÄ·½·¨,Ëû¾ÍÊÇcall,applyËû¿ÉÒԸıäthis µÄÖ¸Ïò;
 var text = {
name : "we are good",
say : function(){
alert(this.name);
}
}
var pest ={
name : "we are pest"
}//¿ÉÒÔ¿´µ½pestûÓÐsayÕâ¸ö·½·¨
text.say.call(pest);//¿ÉÒÔ¿´µ½alert³öÀ´µÄÊÇwe are pest
text.say.apply(pest);
»¹ÓÐÒ»ÖÐÇé¿ö¾ÍÊÇÀàÁË, jsÖеÄÀà¾ÍÊÇfunctionÂð,µ±newÒ»¸öfunctionµÄʱºò¾Í»áÉú³ÉÒ»¸ö¶ÔÏó(Ò²²»Ò»¶¨°¡ µ±ÔÚijЩÇé¿öÏ»¹»áÊÇfunction  Èç¹¹ÔìÀà ÏÖÔÚÎÒ˵µÄÊÇ»ù±¾µÄ)  this ¾ÍÖ¸ÏòÕâ¸ö¶ÔÏóÁË
 function perseon(name){
this.name = name;
this.say = function(){
alert(this.name)
}
}
var wt = new perseon('wt');
wt.say(); //Ö¸ÏòµÄwt
var taozi = new perseon('taozi');
taozi.say();//Ö¸ÏòµÄtaozi
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