Question

I’m using a library which has already defined an onclick event handler on a hyperlink eg:

<a onclick="$('#myDiv').load('/?__=634285190817664832&sort=Id&sortdir=ASC&page=1 #myDiv');" href="#">1</a>

How can I get the value of the ‘url’ parameter?

Answer 1

Updated Answer

…after tobyodavies pointed out (in the nicest of ways) that I was being thick. If you explicitly retrieve the attribute, rather than the reflected property, we’ll get back the string from the DOM, not a function, and so don’t have to worry about function decompilation (see notes below). The remainder of the below is a bit paranoid (because I originally was working from function decompilation), but still:

jQuery(function($) {

  var link, onclick, url, index;

  link = $('#theLink')[0];
  // IMPORTANT: Getting the *attribute* here, not the reflected property.
  // jQuery's `attr` function will give you the property, so go direct.
  onclick = link.getAttribute("onclick");
  display("onclick = " + onclick);
  index = onclick.indexOf("load('");
  if (index < 0) {
    url = "(unknown)";
  }
  else {
    url = onclick.substring(index + 6);
    index = url.indexOf("');");
    if (index > 0) {
      url = url.substring(0, index);
    }
  }
  display("url = " + url);

  function display(msg) {
    $("<p/>").html(msg).appendTo(document.body);
  }
});​

Live example

Original Answer

Note that here there be dragons. The value of the onclick reflected property by the time you’re accessing it in the DOM is a function object on most browsers, and so you’ll have to use Function#toString, which has never been standardized and some mobile browsers are known to just return “[object Function]”. Most desktop browsers return a decompiled version of the event handler, but that can change at any time.

But now you’re aware of the dragons, you can get it that way. Here’s a somewhat paranoid approach:

jQuery(function($) {

  var link, onclick, url, index;

  link = $('#theLink')[0];
  onclick = "" + link.onclick;
  display("onclick = " + onclick);
  index = onclick.indexOf("load('");
  if (index < 0) {
    url = "(unknown)";
  }
  else {
    url = onclick.substring(index + 6);
    index = url.indexOf("');");
    if (index > 0) {
      url = url.substring(0, index);
    }
  }
  display("url = " + url);

  function display(msg) {
    $("<p/>").html(msg).appendTo(document.body);
  }
});​

Live example