Generating event on Javascript array

Question

How can I generate an event when contents of a Javascript array is modified i.e. an event should be generated when push or pop operations are performed over that particular Javascript array. Basically, I want to track the push, pop operations performed over a particular Javascript array.

Edit :- The solutions which are stated in comments, requires to override the push or pop method. I want to perform it without doing overriding it.

Answer 1

The idea is that Arrays are Objects so you can define properties.

var someArray = []; // a normal array

someArray.push = function() { // this will override the original push method
  // custom code here
  console.log('pushing something..');
  return Array.prototype.push.apply(this, arguments); // original push
};
// now everytime you push something a message will be logged. Change this functionality as you like.

Note: someArray.push() will now be enumerable. If you want to prevent this you can define a 'push' property using Object.property method.

Object.defineProperty(someArray, 'push', {
  enumerable: false, // it's false by default anyway
  value: function() {
    console.log('pushing something..');
    return Array.prototype.push.apply(this, arguments);
   }
});