isEqual.js

/*!
 * Check if two objects or arrays are equal
 * (c) 2021 Chris Ferdinandi, MIT License, https://gomakethings.com
 * @param  {*}       obj1 The first item
 * @param  {*}       obj2 The second item
 * @return {Boolean}       Returns true if they're equal in value
 */
function isEqual (obj1, obj2) {

	/**
	 * More accurately check the type of a JavaScript object
	 * @param  {Object} obj The object
	 * @return {String}     The object type
	 */
	function getType (obj) {
		return Object.prototype.toString.call(obj).slice(8, -1).toLowerCase();
	}

	function areArraysEqual () {

		// Check length
		if (obj1.length !== obj2.length) return false;

		// Check each item in the array
		for (let i = 0; i < obj1.length; i++) {
			if (!isEqual(obj1[i], obj2[i])) return false;
		}

		// If no errors, return true
		return true;

	}

	function areObjectsEqual () {

		if (Object.keys(obj1).length !== Object.keys(obj2).length) return false;

		// Check each item in the object
		for (let key in obj1) {
			if (Object.prototype.hasOwnProperty.call(obj1, key)) {
				if (!isEqual(obj1[key], obj2[key])) return false;
			}
		}

		// If no errors, return true
		return true;

	}

	function areFunctionsEqual () {
		return obj1.toString() === obj2.toString();
	}

	function arePrimativesEqual () {
		return obj1 === obj2;
	}

	// Get the object type
	let type = getType(obj1);

	// If the two items are not the same type, return false
	if (type !== getType(obj2)) return false;

	// Compare based on type
	if (type === 'array') return areArraysEqual();
	if (type === 'object') return areObjectsEqual();
	if (type === 'function') return areFunctionsEqual();
	return arePrimativesEqual();

}