watch

Watches for all changes to a specified property (or properties) of an object and produces a sequence whose elements have the properties { property, value } indicating which property changed and what it was changed to.

Note that this method only works on directly wrapped objects; it will not work on any arbitrary ObjectLikeSequence.

ObjectLikeSequence.watch = function(propertyNames) { /*...*/ }

ObjectLikeSequence.watch = function watch(propertyNames) {
  throw new Error('You can only call #watch on a directly wrapped object.');
}

var obj = {},
changes = [];

Lazy(obj).watch('foo').each(function(change) {
  changes.push(change);
});

obj.foo = 1;
obj.bar = 2;
obj.foo = 3;

obj.foo; // => 3
changes; // => [{ property: 'foo', value: 1 }, { property: 'foo', value: 3 }]