How can I check if a value is of type Map in JavaScript?

Question

I have a variable that could be an Object, a Map, or neither. I can easily check for objects with typeof, but I need to conditionally Map.map() the variable if it is a Map, and typeof doesn't work with maps. Any suggestions?

@DeathWaltz — It’s a JS operator. It’s well documented. — Quentin, Nov 20 '20 at 21:57

score 2 · Accepted Answer · answered Nov 20 '20 at 21:57

2

Use instanceof:

var map = new Map;
console.log(map instanceof Map);

answered Nov 20 '20 at 21:57

Ran Marciano

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score 2 · Answer 2 · answered Nov 20 '20 at 21:57

2

var foo = new Set;
foo instanceof Set; // True!
foo instanceof Map; // False!

answered Nov 20 '20 at 21:57

Or Assayag

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How can I check if a value is of type Map in JavaScript?

2 Answers2