detect.js

/**
 * Cycle detection function
 * Outputs count and grouped cycles with a from key path and to key path.
 * The executing browser should have console.group and .groupEnd functions.
 * 
 * Based on:
 * http://stackoverflow.com/questions/14962018/detecting-and-fixing-circular-references-in-javascript/14962496#14962496
 * 
 * @param  {Object} obj Any js object
 * @return {void}     
 */
function detect(obj) {

	var i = 0, nodes = [], cycles = [], cycle;

	function search(val) {
		var i = 0, node;
		for (; i < nodes.length; i++) {
			node = nodes[i];
			if (node.obj === val) {
				return node;
			}
		}
		return false;
	}

	function conj(arr, key) {
		var narr = [].concat(arr);
		narr.push(key);
		return narr;
	}

	function walk(obj, keys) {

		var key, res;

		if (typeof obj !== 'object') { return; }

		res = search(obj);

		if (res) {
			cycles.push({
				from: keys,
				to: res.keys,
				obj: obj
			});
		} else {
			nodes.push({obj:obj, keys:keys});
			for (key in obj) {
				if (obj.hasOwnProperty(key)) {
					walk(obj[key], conj(keys, key));
				}
			}
		}
	}

	walk(obj, []);

	console.log("\nobj has " + cycles.length + " cycle(s)");

	for(; i < cycles.length; i++) {
		cycle = cycles[i];
		console.group("idx: " + i);
		console.log(JSON.stringify(cycle.from) + ' to ' + JSON.stringify(cycle.to));
		/*console.log(cycle.obj);*/
		console.groupEnd();
	}
}