What is the meaning of “foo(…arg)” (three dots in a function call)?

Question

Can someone tell what is \"...\" in the below code in the \"Intro to Angular\" example?

getHeroes() {
    this.backend.getAll(Hero).then( (heroes: Hero[]) =&         


        

Answer 1

It's a copy of the original array

let args = [7, 3, 8];
var [h] = args.reverse(); // args is now 8, 3, 7

whereas

var [h] = [...args].reverse(); // args is still 7, 3, 8

It can also be used to specify the remaining values of an array

var [first, ...rest] = args; // first = 7, rest = [3, 8]