ObjectObserver

small js library to watch objects for changes

What gets created by this script

The script creates an object on the window with the name 'ObjectObserver'.

The interface of the 'ObjectObserver' object

• methods
  • observe (object, property, callback)
    • listens for changes of the given property on the given object and invokes the callback with the new value, if the value gets set
    • callbacks only get invoked, if the new value is different from the old one
    • unique callbacks get only added once
  • unobserve (object, property, callback)
    • removes the listeners for the property changes of the given object

Example

var f = {
        foo: 'foo'
    },

    cb = function (newVal) {
        console.log(newVal);
    },

    i = document.getElementById('foo');

ObjectObserver.observe(f, 'foo', cb);

console.log(f.foo) // >> foo
f.foo = 'bar'; // >> bar

ObjectObserver.unobserve(f, 'foo', cb);
f.foo = 'baz'; // >> [no output]

Notes

• when deleting an object property which gets observed, the observing of that property gets lost
  • to reenable observing, you have to call ObjectObserver.observe() again