为什么调用split和splice给出空数组？

Question

In this JavaScript, why don't i get azbc ?

var x = "a-b-c".split('-').splice(1, 0, 'z');
alert(x.join(''));

split returns an array containing a , b and c .

Shouldn't splice insert z after a and gives me azbc ?

Why do i get an empty array?

note: i know that what i want can be accomplished by:

var x = "a-b-c".split('-')
x.splice(1, 0, 'z');
alert(x.join(''));

since splice "modifies" the original array itself. shouldn't it modify {a,b,c} to {a,z,b,c} and then be assigned to x ?

got it... the code below helped me to understand.

var x = "a-b-c".split('-')
x = x.splice(1, 0, 'z');
alert(x.join(''));

Answer 1

splice returns the removed items from the array, not the new array:

> x = 'a-b-c'.split('-');
["a", "b", "c"]
> x.splice(1,0,'z');
[]
> x
["a", "z", "b", "c"]
> x.splice(1,1,'x');
["z"]
> x
["a", "x", "b", "c"]

Answer 2

Like Paolo said, splice modifies the array in place http://jsfiddle.net/k9tMW/

var array = "a-b-c".split('-');
array.splice(1, 0, 'z');
alert(array.join(''));

Answer 3

Mozilla Developer Network-Array splice method - Changes the content of an array, adding new elements while removing old elements.

Returns - An array containing the removed elements. If only one element is removed, an array of one element is returned.

var x = "a-b-c".split('-');
x.splice(1, 0, 'z');
document.write(x + "<br />"); 

Answer 4

You have to do like this,

var x = "a-b-c".split('-');
x.splice(1, 0, 'z');
alert(x.join(''));​