Delete getter on Javascript array

Question

I have some code where I use getters in an array and I've run into an issue where delete isn't deleting the element from the array. I'd like to know if there's a way to get delete working.

Here's some toy code that replicates the issue:

let x = [];
Object.defineProperty(x, 0, {
  get: function() {
    return;
  }
});
delete x[0];

edit: Slicing is actually not an option, it seems, since only the elements themselves and not the getters are copied.

When you use a getter, there's no actual `0` property in the array, so there's nothing to delete. — Barmar, Nov 06 '20 at 01:22
So how would I remove the getter then? `delete x[0]` doesn't seem to do anything at all. — user3747260, Nov 06 '20 at 01:25
I did some playing around, basically for an object like that, `delete` turns whatever index into undefined instead of removing it like how `splice` does.. `splice` works for plain out arrays and `delete` for `{entity: instance}` sorta objects — The Bomb Squad, Nov 06 '20 at 01:25
i just learned one of js's technicalities thanks to this.. it was quite helpful — The Bomb Squad, Nov 06 '20 at 01:27

score 4 · Accepted Answer · answered Nov 06 '20 at 01:31

4

You need to define the property with the configurable: true option. Then you can delete it and the getter will be removed.

let x = [];
Object.defineProperty(x, 0, {
  configurable: true,
  get: function() {
    return "fake value";
  }
});
console.log(x[0]);
delete x[0];
console.log(x[0]);

See How do I undo a Object.defineProperty call?

answered Nov 06 '20 at 01:31

Barmar

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We should make the words "dynamic" and "fake" synonymous... just kidding, but it gave me a good laugh. – StackSlave Nov 06 '20 at 01:40
Thanks, this worked. Interesting to note that when defining a getter in an object initializer `configurable` is set to true by default, which would explain why it was working for me elsewhere. Ah javascript. – user3747260 Nov 06 '20 at 01:43

Delete getter on Javascript array

1 Answers1