javascript将数组插入到另一个数组中的代码

var arr1 = ['a', 'b', 'c'];
var arr2 = ['1', '2', '3'];
var index = 1;
arr2.unshift(index, 0);Array.prototype.splice.apply(arr1, arr2);
console.log(arr1);

["a", "1", "2", "3", "b", "c"]