JS: Map.prototype.has

By Xah Lee. Date: . Last updated: .

New in ES2015.

map_obj.has(key)

Return true if key exist in map_obj. Else, false.

// check existence
const m = new Map([ [4, "n4"], [5, "n5"] ]);
console.log(m.has (5)); // true
console.log(m.has (99)); // false

JS Map

  1. the Map Object Tutorial
  2. Iterate Over Map Object
  3. Convert Object to/from Map
  4. Map Filter
  5. Reverse Key/Value

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