How to run a function in JavaScript every time a variable changes?

Is there a way in JavaScript to have something like an event that listens to changes in a variable? so when its value is modified the event triggers and then I can call a function. To put this more into context I have a function which handles the html rendering of an array of objects, and I want that function to be called automatically every time the array is modified.

Thanks.

Answer

Use object.watch^docs and if it is not supported natively look at this implementation: Object.watch() for all browsers?