@a11d/equals/dist/Object.equals.js

A value equality utility library.

import { equals } from './symbol.js';
Object.prototype[equals] = function (other) {
    if (this === other) {
        return true;
    }
    if (!(other instanceof Object)) {
        if (typeof other === 'object' && other !== null) {
            return this[equals](Object.assign({}, other));
        }
        return false;
    }
    if (this.constructor !== other.constructor) {
        return false;
    }
    if ('valueOf' in this && 'valueOf' in other && this.valueOf !== Object.prototype.valueOf && this.valueOf !== Object.prototype.valueOf) {
        return this.valueOf() === other.valueOf();
    }
    const nonUndefinedKeys = Object.keys(this).filter(key => this[key] !== undefined);
    const otherNonUndefinedKeys = Object.keys(other).filter(key => other[key] !== undefined);
    if (nonUndefinedKeys.length !== otherNonUndefinedKeys.length) {
        return false;
    }
    for (const [key, value] of Object.entries(this)) {
        if (value === undefined) {
            continue;
        }
        if (!Object.prototype.hasOwnProperty.call(other, key)) {
            return false;
        }
        if (!Object[equals](value, other[key])) {
            return false;
        }
    }
    return true;
};