IE8 & IE 7: not getting CKEditor.instances in IE8 and below version of IE

[Amit.Mukherjee]

I am trying to attach the change , focus and blur events to my CKEditor instances that are dynamically generated.Find below the code. Its working fine for Ie9 and other browsers but not getting the instances in IE8 and below IE versions. Here is the code.

<script type="text/javascript">
        if (window.addEventListener) {

            window.addEventListener('load', onpageload, false);

        }
        else {

            window.attachEvent('onload', onpageload);
        }
    </script>

and the function is :

function onpageload(e) {
    var dirtyField = document.getElementById("dirtyfield");
    for (var i in CKEDITOR.instances) {
        CKEDITOR.instances[i].on('change', function () { dirtyField.value = true; });
        CKEDITOR.instances[i].on('focus', function () {
            this.document.$.childNodes[1].childNodes[1].style.backgroundColor = '#ebf5d0';
        });
        CKEDITOR.instances[i].on('blur', function () {
            this.document.$.childNodes[1].childNodes[1].style.backgroundColor = '#FFFFFF';
        });
    }
}   

Unable to get the instances in IE8 so the code in not able to loop and attach the events with the instances.