isMap()

isMap(value): value is Map<unknown, unknown>

Checks if a value is a Map instance.

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Parameters

value: unknown

The value to check.

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Returns: value is Map<unknown, unknown>

true if the value is a Map, false otherwise.

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See Also

• isSet
• isWeakMap

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Since

2.0.0

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Example

isMap(new Map());              // => true
isMap(new Map([['a', 1]]));    // => true
isMap({});                     // => false
isMap(new WeakMap());          // => false

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How it works?

Type guard that checks if a value is a Map.

Type Narrowing

Common Checks

Value	Result
new Map()	true
new Map([['a', 1]])	true
new WeakMap()	false
{}	false
Object.fromEntries([])	false

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Use Cases

Identify key-value collections 📌

Check if a value is a standard Map object. Perfect for distinguishing Maps from plain objects or other iterables.

#identify#Map#collections#key-value#cache#storage

if (isMap(cache)) {
  cache.set(key, value);
}