JS: Map.prototype.get
(new in ECMAScript 2015)
mapObj.get(key)-
Return the value of the key key in map mapObj.
If key isn't found, return undefined.
const xx = new Map([[4, "n4"], [5, "n5"]]); // get the value of a key console.assert(xx.get(5) === "n5"); console.assert(xx.get(99) === undefined);