hasIn (Lodash compatibility)

Use the in operator instead

This hasIn function performs slowly due to complex path parsing and prototype chain checking.

Instead, use the faster and more modern in operator or Object.hasOwn() function.

Checks if a property at the specified path exists in the object, including inherited properties.

const exists = hasIn(object, path);

Reference

hasIn(object, path)

Use hasIn when you want to check if an object has a property at a specific path. Unlike has, it also checks inherited properties (properties in the prototype chain).

import { hasIn } from 'es-toolkit/compat';

// Check own properties
const object = { a: 1, b: 2 };
hasIn(object, 'a');
// => true

// Check nested objects
const nested = { a: { b: { c: 3 } } };
hasIn(nested, 'a.b.c');
// => true
hasIn(nested, ['a', 'b', 'c']);
// => true

// Non-existent property
hasIn(nested, 'a.b.d');
// => false

// Check array indices
const array = [1, 2, 3];
hasIn(array, 2);
// => true
hasIn(array, 5);
// => false

It also checks inherited properties.

import { hasIn } from 'es-toolkit/compat';

// Check properties in the prototype chain
function Rectangle() {}
Rectangle.prototype.area = function () {};

const rect = new Rectangle();
hasIn(rect, 'area'); // true - finds inherited properties too
has(rect, 'area'); // false - has only checks own properties

Safely handles null and undefined.

import { hasIn } from 'es-toolkit/compat';

hasIn(null, 'a');
// => false

hasIn(undefined, 'b');
// => false

Parameters

• object (any): The object to inspect.
• path (PropertyPath): The path of the property to check. This can be represented as a string, number, symbol, or array.

Returns

(boolean): Returns true if the property at the path exists (whether it's an own property or inherited property), otherwise false.