JavaScript concat two Map objects

Question

Is there any way to concat two (or more) Map Objects to a Map like array concat?

var map1 = new Map([['breakfast', 'meal'], ['dinner', 'meal']]);
var map2 = new Map([['launch', 'meal'], ['dinner', 'meal']]);
var concatenated = map1.concat(map2);

score 25 · Accepted Answer · answered Apr 30 '16 at 20:30

25

The simplest way I found was to convert maps to key value pair array, concat them and finally create a new map from result:

var map1 = new Map([['breakfast', 'meal'], ['dinner', 'meal']]);
var map2 = new Map([['launch', 'meal'], ['dinner', 'meal']]);
var concatenated = new Map([...map1].concat([...map2]));

answered Apr 30 '16 at 20:30

Morteza Tourani

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A simple `new Map([...map1, ...map2])` works too – vaultah Apr 30 '16 at 20:34
Getting error : `Type map is not an array type or a string type` – tryingToLearn Jun 24 '21 at 14:43
@tryingToLearn Which solution? Mine or vaultah's? Share some code to see what's the problem – Morteza Tourani Jun 25 '21 at 22:58

JavaScript concat two Map objects

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