再解javascript中的作用域链

var a=5;

function t(){

var b=5;

function t1(){

var c=7;

alert(a+b+c);

}

t1();

}

t();//18

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var a=5;

function t(){

var b=5;

function t1(){

var c=7;

var b=3

alert(a+b+c);

}

t1();

}

t();//15

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var 的作用

function t1(){

var d;

functiion t2(){

d=5;

e=6;

}

t2();

}

t1();

console.log(e);//6

console.log(d);//d is not defined 错误

console.log(window.e)//undefined