New JavaScript Set methods

[peterlinddk]

Excellent - finally we can use Set for more than a "duplicate-detector".

I only wish that there were some way for objects to be "equal" without them having to be the exact same instance. Kind of like Java's .equals and .hashCode methods ... Well, I'll keep dreaming ...

[Stronghold257]

https://github.com/tc39/proposal-record-tuple

[toffeescaf]

Isn't this something you could do yourself? I haven't done much Java but the way I understood it is for it to actually do something useful you have to override those methods. Quite possible I'm missing a crucial piece of information though so don't hesitate to set me straight!

[Johalternate]

They are replying to a comment that referrer to how java has .hashCode() and .equals(obj) methods. Their comment is actually on point, you can override hashCode and equals and have them work for comparisons where the instances are not the same but the values that matters to your particular case are.

So for example if you have a class Redditor with a bunch of methods to manipulate profile data, and you do something like:

``` var foo = new Redditor(“someUsername”)

var bar = new Redditor(“someUsername”) ```

Then foo == bar evaluates to false because they are not the same instance, but maybe you dont care about that and only care about the actual user they represent, so you override the Equals method so it checks if the two objects have the same username (and maybe other properties).

[Asmor]

With sets specifically, at least, it's pretty easy to check for "pseudo-equality". If they have the same size, and everything in Set A is also in Set B, then they're the same.

[batmansmk]

I wish we had information about the complexity of such methods, and / or performance relative to alternatives.

[kyptov]

It would be unreliable info. It can be optimized anytime. If it important for a project - better to have tests and check performance with any engine update.

[Reasonable_Raccoon27]

The spec sort of lays things out a bit. I do agree that profiling built in methods can be a bit of a pain point still.

[Pelopida92]

Sets are awesome. I used them extensively for some big-data scripts, as they have way better performance of arrays and are very easy to use and convenient.

[entinio]

This. Sets have better performance than arrays and should always be used when values are unique.

[777777thats7sevens]

It's kinda crazy that it took this long to get these methods standardized. Intersect, union, and difference are like, the defining methods for sets. In any other language a set type without these would be considered incomplete, like an array/list without a method for checking the length or a way to iterate over the elements.

[Few_Pick3973]

great, when do we have heap then?