javascript闭包入门示例

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我是靠谱客的博主平淡柠檬，最近开发中收集的这篇文章主要介绍javascript闭包入门示例，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

复制代码代码如下:

functionsay667(){
varnum=666;
varsayAlert=function(){alert(num);}
num++;
returnsayAlert;
}

varsayAlert=say667();
sayAlert();

复制代码代码如下:

functionsetUpSomeGlobals(){
varnum=666;
gAlertNumber=function(){alert(num);}
gIncreaseNumber=function(){num++;}
gSetNumber=function(x){num=x;}
}

setUpSomeGlobals();//为三个全局变量赋值
gAlertNumber();//666
gIncreaseNumber();
gAlertNumber();//667
gSetNumber(12);
gAlertNumber();//12

复制代码代码如下:

functionbuildList(list){
varresult=[];
for(vari=0;i<list.length;i++){
variteml='item'+list[i];
result.push(function(){alert(item+''+list[i]);});
}
returnresult;
}

functiontestList(){
varfnlist=buildList([1,2,3]);
for(varj=0;j<fnlist.length;j++){
fnlist[j]();
}
}

复制代码代码如下:

functionsayAlice(){
varsayAlert=function(){alert(alice);}
varalice='HelloAlice';
returnsayAlert;
}

varhelloAlice=sayAlice();
helloAlice();//HelloAlice

复制代码代码如下:

functionnewClosure(someNum,someRef){
varnum=someNum;
varanArray=[1,2,3];
varref=someRef;
returnfunction(x){
num+=x;
anArray.push(num);
alert('num:'+num+'nanArray'+anArray.toString()+'nref.someVar'+ref.someVar);
}
}

closure1=newClosure(40,{someVar:'closure1'});
closure2=newClosure(1000,{someVar:'closure2'});

closure1(5);
closure2(-10);