Javascript/AJAX not working in Opera, works perfec

问题:

I currently have this Javascript in a file named getresults.js:

function getItems(str)
{
if (str=="")
  {
  document.getElementById("getItems").innerHTML="";
  return;
  }
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("getItems").innerHTML=xmlhttp.responseText;
    }
  }
xmlhttp.open("GET","/include/retrieveitems.php?q="+str,true);
xmlhttp.send();
}

It's called upon by this event:

onclick="getItems('all')"

It works perfectly in Firefox, IE, Chrome.. but Opera refuses to work. A very small percentage of my visitors are Opera users, but still.. I'd rather have it work. A live url can be found here: http://tf2g.com/gallery

If anyone can help, much obliged!

回答1:

The reason this fails is that the event handler is not calling your getItems() method at all. It sees the document.getItems() method from Opera's Microdata support ( http://www.whatwg.org/specs/web-apps/current-work/multipage/microdata.html ) and calls that instead. It's a question of JavaScript scope: both the element itself and its document is in scope, so methods/properties defined here will be able to hide methods / properties you define in the global scope.

Be happy that Opera implemented Microdata early so you noticed this :)

The simplest fix is to rename your function to avoid name collision with Microdata. You can also use addEventListener() instead of writing onclick="" in the markup - if you do the scope of the function is the scope it is created in, so you don't run into such gotchas.

window.addEventListener('load', function(){
  for( var i=0,l;l=document.links[i]; i++ )if( l.hash){
    l.addEventListener( 'click', function(){
      getItems(this.hash.substr(1));
    }, false);
  }
}, false);

回答2:

I debugged your link a bit and found out that there's no problem with the AJAX request. In fact, there's an unhandled exception in jquery.min.js file which prevents other javascript code from running.

Steps I did: I opened Opera DragonFly (Ctrl+Shft+I), which is firebug-a-like and refresh the page. I inserted break-points in 'getItems()' and saw that the code didn't reach there. Via Dragonfly console I wrote "getItems('all');" and the ajax went as expected.

O