案例1:var n=10;function fun(){ var n=100; //n为局部变量 n++; console.log(n);}fun(); //101console.log(n); //10案例2:
var n=10;function fun(){ /*var*/ n=100; //n为全局变量 n++; console.log(n);}fun(); //101console.log(n); //101