dictionary - How can I get a key in a JavaScript 'Map' by its value?

Question

I have a JavaScript 'Map' like this one

let people = new Map();
people.set('1', 'jhon');
people.set('2', 'jasmein');
people.set('3', 'abdo');

I want some method to return a key by its value.

let jhonKey = people.getKey('jhon'); // jhonKey should be '1'

Answer 1

You could convert it to an array of entries (using [...people.entries()]) and search for it within that array.

let people = new Map();
people.set('1', 'jhon');
people.set('2', 'jasmein');
people.set('3', 'abdo');
    
let jhonKeys = [...people.entries()]
        .filter(({ 1: v }) => v === 'jhon')
        .map(([k]) => k);

console.log(jhonKeys); // if empty, no key found otherwise all found keys.