forIn

INFO

This function is only available in es-toolkit/compat for compatibility reasons. It either has alternative native JavaScript APIs or isn't fully optimized yet.

When imported from es-toolkit/compat, it behaves exactly like lodash and provides the same functionalities, as detailed here.

Iterates over an object and invokes the iteratee function for each property.

Iterates over string keyed properties including inherited properties.

The iteration is terminated early if the iteratee function returns false.

Signature

function forIn<T>(object: T, iteratee?: (value: T[keyof T], key: string, collection: T) => any): T;
function forIn<T>(
  object: T | null | undefined,
  iteratee?: (value: T[keyof T], key: string, collection: T) => any
): T | null | undefined;

Parameters

• object (T | null | undefined): The object to iterate over
• iteratee ((value: T[keyof T], key: string, collection: T) => any): The function invoked per iteration. Default is the identity function

Returns

(T | null | undefined): Returns object

Examples

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

function Shape() {
  this.x = 0;
  this.y = 0;
}

Shape.prototype.move = function (x, y) {
  this.x += x;
  this.y += y;
};

// Create an instance of Shape
const square = new Shape();

// Iterate over all enumerable properties (including inherited ones)
forIn(square, function (value, key) {
  console.log(key, value);
});
// Output:
// 'x', 0
// 'y', 0
// 'move', [Function]

// The iteration is terminated early if the iteratee returns false
forIn(square, function (value, key) {
  console.log(key, value);
  return key !== 'y'; // stop at 'y'
});
// Output:
// 'x', 0
// 'y', 0