Sets

Added in ES 2015.
A set is a specialised array that can only contain one instance of each unique item.
You can create a new instance of Set by passing a flat array as an argument.

const mySet = new Set() 
mySet.add('value')  

const myArray = ['value1','value2','value2'];  
mySet = new Set(myArray) 
// Set {'value1', 'value2'} 

Methods