object-diff.js

// Only dependency is the lodash library

function deepDiff(oldObj, newObj) {
  // Instantiate our changes obj
  var changes = {};
  
  // Make sure we are working with objects
  oldObj = _(oldObj).value();
  newObj = _(newObj).value();
  
  function merge(oldObj, newObj, parent) {
    // Attempt to merge old and new objects, and highjack the values in a callback
    _.merge(oldObj, newObj, function (oldValue, newValue, key) {
      // Make sure we are dealing with different values
      if (!_.isEqual(oldValue, newValue)) {
        // If current value is an object, we need to set instantiate a new object
        // and recurse through the changed object's children
        if (_.isObject(newValue)) {
          parent[key] = {};
          merge(oldValue, newValue, parent[key]);
        } else {
          // Otherwise we set the value
          parent[key] = newValue;
        }
      }
    });
  }
  
  // Start it off
  merge(oldObj, newObj, changes);

  return changes;
}