JavaScript: Set.prototype.add
New in JS2015.
setObj.add(value)
Add value to the set setObj.
Return the modified set.
// create a set, add value to it const s = new Set(); s.add (6); s.add (5); s.add (6); // the set is modified console.log(s); // Set { 6, 5 } console.log( s.add (7)); // Set { 6, 5, 7 } // the method “add” returns the modified set