Fastest way to do Array A = Array B without changing the reference of A

Question

I have an array A and a function that generates me an array B

var A = ["test"];
var B = ["hello", "world"];
var C = A;

How to make it so A = B (contains all and only the values in B) without changing its reference, so C also contains all and only the values in B.

possible duplicate of: stackoverflow.com/questions/7486085/… — guysigner
– guysigner, Commented Feb 5, 2016 at 8:05
If you set C = A first, then setting A = (Anything) won't affect C in any condition. — Ali
– Ali, Commented Feb 5, 2016 at 8:08
@remdevtec that's not quite what OP is asking. I believe he is specifically asking how to change the underlying pointer of A to point to B after C has already been pointed to A. So, after changing the reference, printing C would in fact print the contents of B. I'm fairly sure this isn't possible based on the quesiton/answer stackoverflow.com/questions/6605640/… — Matthew Herbst
– Matthew Herbst, Commented Feb 5, 2016 at 8:08
remdevtex and Unknown users, the suggested duplicates are not duplicates. They do not apply to keeping the same array and make a copy instead. — Arnaud Weil
– Arnaud Weil, Commented Feb 5, 2016 at 8:19

Arnaud Weil · Accepted Answer · 2016-02-05 08:13:06Z

5

I'd suggest:

A.splice(0);
A.push.apply(A, B);

Splice will remove all of the items from A. Push will add the items from B to A. Except push takes an argument list, not an array, so we call apply in order to convert the array into arguments.

Working example here.

edited Feb 5, 2016 at 8:13

answered Feb 5, 2016 at 8:10

Arnaud Weil

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2 Comments

zerkms Over a year ago

It's not obvious what the A.push.bind(A, B); line is supposed to do.

Arnaud Weil Over a year ago

Sorry, I had an error, just fixed: you need to call apply, not bind.

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