Function isObject

isObject<T>(
value: T,
): value is T extends Function | unknown[] ? never : T & object

Checks if a value is typeof object and not null or an array.

Type Parameters

Parameters

value: T
The value to check.

Returns value is T extends Function | unknown[] ? never : T & object

true if the check passes, false otherwise.

Remarks

This function will return false for an array. If you do not want this behavior, use isObjectLoose instead.

Example

Basic usage

isObject({}) // true
isObject([]) // false
isObject(null) // false

Type narrowing

const value: { foo: string } | string[]

if (isObject(value)) {
  value // type: { foo: string }
} else {
  value // type: string[]
}

// works with function too
const value: { foo: string } | (() => string)

if (isObject(value)) {
  value // type: { foo: string }
  value.foo // ok
} else {
  value // (() => string)
  value() // ok
}

Paired with assert

import { assert } from 'uft'

const options: { opt: string } | string[]
assert(isObject(options), 'expected options object')
options // type: { opt: string }