isObject function

Checks whether a value is a non-null object: plain object, array, class instance, date… isRecord accepts plain objects only.

import { isObject } from 'utils';

Signature

export function isObject(value: unknown): value is object

Parameters

Name	Description
value	The value to check.

Returns

true for any non-null object; false for a function.

Example

isObject([]); // true
isObject(null); // false

Tests

Line coverage: 100 %.

• ✅ checks {} as true
• ✅ checks [] as true
• ✅ checks {"x":0} as true
• ✅ checks "1970-01-01T00:00:00.000Z" as true
• ✅ checks null as false
• ✅ checks undefined as false
• ✅ checks "object" as false
• ✅ checks undefined as false

Source

src/guard/is-object.ts (on GitHub)

Used by

• isDeepEqual: Checks whether two values are equal at every depth: primitives (NaN equals NaN), arrays, objects with the same prototype, Date, RegExp, Map, Set and typed arrays.
• isShallowEqual: Checks whether two values are equal at the first level, with Object.is: skips an update when a new object carries the same values as the previous one.

Source code

/**
 * Checks whether a value is a non-null object: plain object, array, class instance, date… `isRecord` accepts
 * plain objects only.
 *
 * @param value - The value to check.
 * @returns `true` for any non-null object; `false` for a function.
 * @example
 * isObject([]); // true
 * isObject(null); // false
 */
export function isObject(value: unknown): value is object {
  return typeof value === 'object' && value !== null;
}

Test file

import { isObject } from './is-object';

class Point {
  public readonly x = 0;
}

// Plain function type: calls are not seen as conditions, so any value can be passed.

describe(isObject, () => {
  it.for([
    [{}, true],
    [[], true],
    [new Point(), true],
    [new Date(0), true],
    [null, false],
    [undefined, false],
    ['object', false],
    [(): number => 0, false],
  ] as const)('checks %j as %s', ([value, expected]) => {
    expect(isObject(value)).toBe(expected);
  });
});

Keywords: is, object, guards, function