JavaScript Map_basics Guide
Map stores key-value pairs with any type of key, maintaining insertion order and providing better performance than objects. The guide walks through Map & WeakMap. `new Map()` — create. `.set(k, v)` — set. `.get(k)` — get. `.has(k)` — check. `.delete(k)` — remove. `.size` — entries. `.clear()` — empty. Keys: any type (objects, functions, primitives). Iteration: forEach, for...of (entries, keys, values). WeakMap: keys must be objects, no iteration, prevents memory leaks. The guide is organized into 1 sections that build on each other, each pairing a prose explanation with runnable code. Related guides: Arrays, Strings, Numbers, Math, Date. This is one of 145 JavaScript guides on JS Reference — see the full list on the guides page. Practice what you learn in the JavaScript playground, and look up any unfamiliar term in the JavaScript glossary.