JS——坑9

var a = 1;function test(){//变量提前到这里 var a;//var a;console.log(a);var a = 1;}test(); //undefined

c = 5;function test3(){window.c = 3;console.log(c);//undefined  因为var c会提前，而且这里会输出局部cvar c;console.log(window.c);//3}test3();