Why doesn't Array.push.apply work?
JavascriptArraysApplyJavascript Problem Overview
As described here, a quick way to append array b to array a in javascript is a.push.apply(a, b)
.
You'll note that the object a is used twice. Really we just want the push
function, and b.push.apply(a, b)
accomplishes exactly the same thing -- the first argument of apply supplies the this
for the applied function.
I thought it might make more sense to directly use the methods of the Array object: Array.push.apply(a, b)
. But this doesn't work!
I'm curious why not, and if there's a better way to accomplish my goal. (Applying the push
function without needing to invoke a specific array twice.)
Javascript Solutions
Solution 1 - Javascript
It's Array.prototype.push
, not Array.push
Solution 2 - Javascript
You can also use [].push.apply(a, b)
for shorter notation.
Solution 3 - Javascript
The current version of JS allows you to unpack an array into the arguments.
var a = [1, 2, 3, 4, 5,];
var b = [6, 7, 8, 9];
a.push(...b); //[1, 2, 3, 4, 5, 6, 7, 8, 9];
Solution 4 - Javascript
What is wrong with Array.prototype.concat
?
var a = [1, 2, 3, 4, 5];
var b = [6, 7, 8, 9];
a = a.concat(b); // [1, 2, 3, 4, 5, 6, 7, 8, 9];