Spread Operator (…) in JavaScript

… called as spread operator

Usage:

concatenate two or more arrays

const newList = […firstList, …secondList, …etcLists]

concatenate two or more objects

const newObject = {…firstObject, …secondObject, …etcObjects}

… in function arguments

const list = [1,3]
function sum(a,b){
return a+b;
}

sum(…list)

This is how … (spread operator) used.