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isMap()

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

Checks if a value is a Map instance.

Parameters​

value: unknown​

The value to check.

Returns: value is Map<unknown, unknown>​

true if the value is a Map, false otherwise.

See Also​

Since​

2.0.0

Example​

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

How it works?​

Type guard that checks if a value is a Map.

Type Narrowing​

Common Checks​

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

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.

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