[removed] Adding an onClick handler without overwriting the existing one

Question

I\'m trying to modify all links on a page so they perform some additional work when they are clicked.

A trivial approach might be something like this:

Answer 1

Use a wrapper around addEventListener (DOM supporting browsers) or attachEvent (IE).

Note that if you ever want to store a value in a variable without overwriting the old value, you can use closures.

function chain(oldFunc, newFunc) {
  if (oldFunc) {
    return function() {
      oldFunc.call(this, arguments);
      newFunc.call(this, arguments);
    }
  } else {
    return newFunc;
  }
}

obj.method = chain(obj.method, newMethod);

In Aspect Oriented Programming, this is known as "advice".