解构数组 var [a,b]=[1,2]; a //1 b //2 ------------- var [a,b]=[1,2,3,4]; a //1 b //2 ---------------- var [a,,b]=[1,2,3,4]; a //1 b //3 ----------------- var a,b; [a=3,b=2]=[1]; //默认值 a //1 b //2 ----------------- var [a, ...b] = [1,2,3,4] a //1 b // [2,