This site is mobile accessible. Press the "Tap Here" button to use a smaller font-size.

Smartphone icons created by Freepik - Flaticon

JavaScript Maps

Using Map.size:

// Create a Map
const fruits = new Map([
  ["apples", 500],
  ["bananas", 300],
  ["oranges", 200]
]);

document.getElementById("demo").innerHTML = fruits.size;

The size property returns the number of elements in a Map: