array.length-=1 vs array.pop()

Question

I know that array is some kind of an object, but it also has numeric indexes. And arr.length is a property, which returns not the number of elements in the array, but the last index+1. We can remove the last element using decrement of length or function pop(). And the question is: What's the difference between these methods?

you get the item with `pop`...? what is the changing of length for? — Nina Scholz, Jul 06 '19 at 16:57
[Is it an antipattern to set an array length in JavaScript?](https://stackoverflow.com/questions/31547315) and [Javascript array length modification implications](https://stackoverflow.com/questions/43712345) — adiga, Jul 06 '19 at 17:00

score 8 · Accepted Answer · answered Jul 06 '19 at 17:03

Some differences:

pop returns the value of the entry that you're removing, assigning to length doesn't.
pop is a method call; assigning to length is an assignment operation.
pop on an array whose length is 0 returns undefined and doesn't change the array. array.length -= 1 on an array with a length of 0 causes an error.

score 3 · Answer 2 · edited Oct 16 '22 at 09:49

3

.pop() also returns the last element (which is often wanted):

const last = array.pop();
// vs
const last = array[array.length - 1];
array.length -= 1;

Now you can decide yourself which one of the above is more readable ...

edited Oct 16 '22 at 09:49

Donald Duck

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answered Jul 06 '19 at 16:59

Jonas Wilms

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array.length-=1 vs array.pop()

2 Answers2