isIterable

Checks whether a value is iterable. A value is iterable if it is not null or undefined and has a callable [Symbol.iterator] method. This matches the behavior of for...of, spread syntax, and Array.from.

Signature

function isIterable<T = unknown>(value: unknown): value is Iterable<T>

Parameters

Name	Data type	Description
value	unknown	The value to check. Must implement the iterable protocol to return true.

Returns

A boolean:

• true: If the value is iterable.
• false: Otherwise.

Examples

isIterable([1, 2, 3])        // true
isIterable('abc')            // true
isIterable(new Set())        // true

isIterable({})               // false
isIterable(123)              // false
isIterable(null)             // false

Notes

• This helper checks only for the presence of a callable [Symbol.iterator] method.
• Array-like objects (objects with numeric length but without a [Symbol.iterator] method) are not considered iterable by this helper.
• It does not attempt to call the iterator.
• It does not treat array‑like objects as iterable unless they implement the iterator protocol.
• Use validateIterable if you need a Result<T> instead of a boolean.

Next up

isPromise