JS: Map.prototype.set

New in JS2015.

mapObj.set(key, val)

Add a entry to the map mapObj . If the key already exist, overwrite its value. Return the modified map.

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

// add entry
const xResult = xx.set(3, "n3");

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

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