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Map & WeakMap

Easy

In plain terms

Map stores key-value pairs. Keys can be any type (unlike objects). Methods: set, get, has, delete, size. WeakMap keys must be objects; allows garbage collection.

What you need to know

  • •Any key type
  • •set, get, has, delete
  • •WeakMap: object keys, weak refs

Try it yourself

Copy the code below and run it in your browser console or a code editor:

const map = new Map();
map.set('name', 'Alice');
map.set(1, 'one');
map.set({}, 'object key');

map.get('name');   // "Alice"
map.has('name');   // true
map.delete('name');
map.size;

for (const [k, v] of map) {
  console.log(k, v);
}

Learn more

Dive deeper with these trusted resources:

MDNjavascript.infoTutorialsPointW3Schools