title: How can I get a key in a JavaScript 'Map' by its value?
body: <p>I have a JavaScript 'Map' like this one</p>
  <pre><code>let people = new Map();
  people.set('1', 'jhon');
  people.set('2', 'jasmein');
  people.set('3', 'abdo');
  </code></pre>
  <p>I want some method to return a key by its value.</p>
  <pre><code>let jhonKey = people.getKey('jhon'); // jhonKey should be '1'
  </code></pre>