Question

I’m trying to create a collapsable list in Internet Explorer 8 for the HTML I have:

<li>
 <a href="#" onclick="test('node1')">hello</a>
 <ul id="node1" class="node" style="display:none">
   <li>Sub-item 1</li>
   <li>Sub-item 2</li>
 </ul>
</li>
<li>
 <a href="#" onclick="test('node2')">test</a>
  <ul id="node2" class="node" style="display:none">
   <li>Sub-item 1</li>
   <li>Sub-item 2</li>
 </ul>
</li>

in javascript i have

function test2(className, link) {
 var e = document.getElementsByClassName(className);

 for (var i = 0, len = e.length; i < len; i++) {
   e[i].style.display = "none";
  }

  link.innerHTML = "Expand";
 }

I’m using this to call it:

      <a href="#" onclick="test2('node', this)">Collapse</a>

Unfortunately, this method is not working in IE8, and neither is querySelectAll. Can someone provide an example how to fix this please?

Answer 1

Here is a quick solution by extending the Element.prototype and the document:

(function() {
if (!document.getElementsByClassName) {
    var indexOf = [].indexOf || function(prop) {
        for (var i = 0; i < this.length; i++) {
            if (this[i] === prop) return i;
        }
        return -1;
    };
    getElementsByClassName = function(className, context) {
        var elems = document.querySelectorAll ? context.querySelectorAll("." + className) : (function() {
            var all = context.getElementsByTagName("*"),
                elements = [],
                i = 0;
            for (; i < all.length; i++) {
                if (all[i].className && (" " + all[i].className + " ").indexOf(" " + className + " ") > -1 && indexOf.call(elements, all[i]) === -1) elements.push(all[i]);
            }
            return elements;
        })();
        return elems;
    };
    document.getElementsByClassName = function(className) {
        return getElementsByClassName(className, document);
    };

    if(Element) {
        Element.prototype.getElementsByClassName = function(className) {
            return getElementsByClassName(className, this);
        };
    }
}
})();

It’s not always, however, the best idea to extend the prototype object, especially with a function named exactly like a non-existent native function. If you want to escape the problems caused by extension of the prototype, use this code:

(function() {
    var indexOf = [].indexOf || function(prop) {
        for (var i = 0; i < this.length; i++) {
            if (this[i] === prop) return i;
        }
        return -1;
    };
    window.getElementsByClassName = function(className,context) {
        if (context.getElementsByClassName) return context.getElementsByClassName(className);
        var elems = document.querySelectorAll ? context.querySelectorAll("." + className) : (function() {
            var all = context.getElementsByTagName("*"),
                elements = [],
                i = 0;
            for (; i < all.length; i++) {
                if (all[i].className && (" " + all[i].className + " ").indexOf(" " + className + " ") > -1 && indexOf.call(elements,all[i]) === -1) elements.push(all[i]);
            }
            return elements;
        })();
        return elems;
    };
})();​

That way, you can safely use a getElementsByClassName() function that accepts two arguments:

1. className: the CSS class
2. context: the node