Map and WeakMap getOrInsert() and getOrInsertComputed()

Reading or inserting `Map` and `WeakMap` entries in one call with ES2026's upsert methods, for counters, groups, nested maps and caches.

Content tagged map-upsert

• Post:What's New in ES2026: Every Feature Explained

  Every ES2026 feature, with examples and browser support.

  Every ES2026 feature with examples: Map upsert, JSON.parse source text, Iterator.concat, Uint8Array Base64, Math.sumPrecise, Error.isError and Array.fromAsync.