JavaScript map() constructor | Create map object

Using JavaScript map() constructor, you can creates Map objects. The map object is a data structure that stores elements as a key-value pair.

new Map()
new Map(iterable)

JavaScript map constructor

Simple example code creating a new Map. A new Map object returns after the initialization of the map constructor.

<!DOCTYPE html>
<html>
<body>
  <script >
    let myMap = new Map([
      [1, 'one'],
      [2, 'two'],
      [3, 'three'],
      ]);
    
    console.log(myMap)

  </script>
</body>
</html>

Output:

JavaScript map() constructor | Create map object

Return key for JS Map constructor with value

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.

Output: [ “1” ]

Do comment if you have any doubts or suggestions on this Js map() tutorial.

Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version

JavaScript map() constructor | Create map object