Compare list 1 and 2 -> put missing elements in extra list (without foreach)

[basmail]

Hello everybody!

I have a problem, I need all missing elements in a separate list

List 1

• A
• C
• D

List 2

• A
• B
• C
• D

The only element in List 3 needs to be

• B

How do I solve this most efficiently? A foreach would take too long for my purpose.
Maybe I'll over think this and there is a simple solution but i dont get it rn.

Thanks for helping :)

[GaG]

https://stackoverflow.com/questions/1187518/how-to-get-the-difference-between-two-arrays-in-javascript

[basmail]

Works great for me:

Array.prototype.diff = function(a) {
    return this.filter(function(i) {return a.indexOf(i) < 0;});
};

const dif = [[TABLE1]].diff([[TABLE2]]);
[[DIF]] = (dif);