Tips for Golfing in ECMAScript 6 and above
Spread operator ...

The spread operator transforms an array value into a comma separated list.

Use case 1:

Directly use an array where a function expects a list

list=[1,2,3]
x=Math.min(...list)
list=[10,20], a.push(...list) // similar to concat()


Use case 2:

Create an array literal from an iterable (typically a string)

[...'buzzfizz'] // -&gt; same as .split('')


Use case 3:

Declare a variable number of arguments for a function

F=(...x) =&gt; x.map(v =&gt; v+1)
// example: F(1,2,3) == [2,3,4]


See mozilla doc