Deep watcher over objects

deep-object-watcher.js

if (!Object.prototype.deepWatch) {
	Object.prototype.deepWatch = function(f) {
		let res = {};
		Object.keys(this).forEach(k => {
			let src = this[k];
			if (Array.isArray(src)) {
				res[k] = new Proxy(src, {
					set(src, i, val) {
						if (i !== "length") f.call(this, src, [...src, val]);
						return Reflect.set(...arguments);
					},
					get() { return Reflect.get(...arguments); }
				}); 
			} else if (typeof src === "object") {
				res[k] = this[k].deepWatch(f);
			} else if (typeof src !== "function") {
				let _k = `_${ k }`;
				res[_k] = src;
				Object.defineProperty(res, k, {
					set(val) {
						f.call(this, this[_k], val);
						this[_k] = val;
					},
					get() { return this[_k]; }
				});
			} else {
				res[k] = src;
			}
		});
		return res;
	}
}