Question

This is the piece of code in question:

       ...     
        var btnClick = document.getElementById("button");
        btnClick .addEventListener("click", func, false);
    }
    function func()
    {
        alert("This works");
    }

I don’t get any alert box. See any problems?

Answer 1

Which browser are you using? IE doesn’t support .addEventListener() until version 9, so you need to say something like this:

var btnClick = document.getElementById("button");

if (btnClick.addEventListener){
  btnClick.addEventListener('click', func, false); 
} else if (btnClick.attachEvent){
  btnClick.attachEvent('onclick', func);
}
// and if you're really keen:
else {
  btnClick.onclick = func;
}

And don’t use .getElementById() on an element that hasn’t been parsed yet, i.e., put the above code either in a document.ready or load event handler, or put it after the element in the page source.