javascript - Javascript concat 方法的结果顺序

Question

连接结果的顺序是否始终保留？

var alpha = ['a', 'b', 'c'];
var numeric = [1, 2, 3];

alpha.concat(numeric);
// result in ['a', 'b', 'c', 1, 2, 3]

Answer 1

是的，是的。

From MDN (强调我的):

The concat method creates a new array consisting of the elements in the object on which it is called, followed in order by, for each argument, the elements of that argument

来自ECMAScript spec (强调我的):

When the concat method is called with zero or more arguments, it returns an array containing the array elements of the object followed by the array elements of each argument in order.