JS: Map.prototype.set

New in ES2015.

map_obj.set(key, val)

Add a entry to the map map_obj . If the key already exist, overwrite its value.

Return the modified map.

// create a map
const mp = new Map();

// add entry
const returnValue = mp.set (3, "n3");

// the map is modified
console.log ( mp );
// Map { 3 => 'n3' }

// returns value is the modified map
console.log ( returnValue );
// Map { 3 => 'n3' }

Reference

ECMAScript 2015 §Keyed Collection#sec-map.prototype.set