Skip to content

Instantly share code, notes, and snippets.

What would you like to do?
Deep (but slow) comparison of JSON-serializable JS objects
// I'm using this now in my Alloy runtime testing to assert that the
// proper styles are getting assigned to Titanium proxy objects. The
// deep comparison is necessary for objects like font in the style. So
// for my purposes the accuracy of the results far supercedes the lack
// of blazing performance with this code. I'm using underscore.js as
// it's part of Alloy, but isX() calls could easily be filled out in
// a couple lines of JS.
// Obviously due to the use of JSON.stringify() the objects to be
// compared need to be JSON serializable.
function sortAndStringify(obj) {
// make use of the JSON.stringify() "replacer" parameter, which allows
// us to transform any given key or value as it is encountered. We'll
// use it to sort any objects (but not arrays or funcs) that we encounter.
return JSON.stringify(obj, function(k,v) {
if (_.isObject(v) && !_.isArray(v) && !_.isFunction(v)) {
return sortObject(v);
return v;
// re-inserts object keys in alphabetical order. This code is not mine, I've
// seen it a couple places. Not sure to whom I should give credit.
function sortObject(o) {
var sorted = {},
key, a = [];
for (key in o) {
if (o.hasOwnProperty(key)) {
for (key = 0; key < a.length; key++) {
sorted[a[key]] = o[a[key]];
return sorted;
// Now I can compare 2 deeply nested JS objects
if (sortAndStringify(object1) === sortAndStringify(object2)) {
// hey, I did a deep comparison!
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment