isPlainObject

Checks if a value is a plain object.

A plain object is a basic JavaScript object, such as {} or { name: 'John', age: 30 }. It is not derived from a class and has either Object.prototype or null as its prototype. When you convert it to a string using the toString method, it will show up as [object Object].

Signature

function isPlainObject(value: unknown): value is Record<PropertyKey, any>;

Parameters

value (unknown): The value to check.

Returns

(value is Record<PropertyKey, any>): True if the value is a plain object, otherwise false.

Examples

isPlainObject({}); // true
isPlainObject([]); // false
isPlainObject(Object.create(null)); // true

class Foo {}
isPlainObject(new Foo()); // false
isPlainObject(new Date()); // false
isPlainObject(new Set()); // false
isPlainObject(new Map()); // false
isPlainObject(Buffer.from('hello, world')); // false
isPlainObject(Math); // false
isPlainObject(JSON); // false
isPlainObject(null); // false
isPlainObject(1); // false

Performance Comparison

	Bundle Size	Performance
es-toolkit	279 bytes (82.4% smaller)	1,505,684 times (1.70× faster)
es-toolkit/compat	435 bytes (72.5% smaller)	2,013,760 times (2.28× faster)
lodash-es	1,586 bytes	882,669 times

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