Object-Oriented JavaScript - Third Edition

Spread operators

A spread operator looks exactly like a rest operator but performs the exact opposite function. Spread operators are used while providing arguments while calling a function or defining an array. The spread operator takes an array and splits its element into individual variables. The following example illustrates how the spread operator provides a much clearer syntax while calling functions that take an array as an argument:

    function sumAll(a,b,c){ 
      return a+b+c 
    } 
    var numbers = [6,7,8] 
    //ES5 way of passing array as an argument of a function 
    console.log(sumAll.apply(null,numbers)); //21 
    //ES6 Spread operator 
    console.log(sumAll(...numbers))//21 

In ES5, it is common to use the apply() function when passing an array as an argument to ...