TypeScript methods cloning and comparing objects using WeakMap and WeakSet

objectHelper.ts

export interface IObject {
    [key: string]: any;
}

export function cloneObject(source: IObject, maxDeep: number = Infinity): IObject {
    if (typeof source !== 'object') {
        throw new Error('Argument must be an object');
    }
    const refs = new WeakMap<IObject, IObject>();
    const dest: IObject = {};

    (function deepSearch(dest: IObject, source: IObject, deep: number = 0): void {
        for (const key of Object.keys(source)) {
            const node = source[key];

            if (node.constructor === Date) {
                dest[key] = new Date(node);
            } else if (typeof node !== 'object' || deep >= maxDeep ||
                node.constructor !== Array && node.constructor !== Object) {
                dest[key] = node;
            } else {
                const ref = refs.get(node);

                if (ref) {
                    dest[key] = ref;
                } else {
                    if (node.constructor === Array) {
                        dest[key] = [];
                    } else {
                        dest[key] = {};
                    }
                    refs.set(node, dest[key]);
                    deepSearch(dest[key], node, deep + 1);
                }
            }
        }
    })(dest, source);

    return dest;
}

export function sameObjects(obj1: IObject, obj2: IObject = {}): boolean {
    if (typeof obj1 !== 'object' || typeof obj2 !== 'object') {
        throw new Error('Arguments must be objects');
    }
    const refs = new WeakSet<IObject>();

    return (function deepSearch(obj1: IObject, obj2: IObject): boolean {
        for (const key of Object.keys(obj1)) {
            const type1 = typeof obj1[key];
            const type2 = typeof obj2[key];

            if (type2 === 'undefined' || type1 !== type2) {
                return false;
            } else if (type1 === 'object') {
                if (!refs.has(obj1[key])) {
                    refs.add(obj1[key]);

                    if (obj1[key].toString() !== obj2[key].toString() ||
                        !deepSearch(obj1[key], obj2[key])) {
                        return false;
                    }
                }
            } else if (type1 === 'function') {
                if (obj1[key].toString() !== obj2[key].toString()) {
                    return false;
                }
            } else if (obj1[key] !== obj2[key]) {
                return false;
            }
        }

        return true;
    })(obj1, obj2);
}