Javascript错误：ie6和ie7中需要对象

Question

I have a javascript function (epoch calendar) which displays a calendar when focus is set on certain text boxes. this works fine in ie8, ff (all versions as far as I can test), opera etc but doesn't work in ie7 or previous.

If i have it set up in a blank html test page it will work so I'm fairly sure it's a conflict with my css (provided to me by a designer).

I've traced the error to these lines of code -

Epoch.prototype.getTop = function (element) //PRIVATE: returns the absolute Top value of element, in pixels
{
    var oNode = element;
    var iTop = 0;

    while(oNode.tagName != 'BODY') {
        iTop += oNode.offsetTop;
        oNode = oNode.offsetParent;
    }

    return iTop;
};

Epoch.prototype.getLeft = function (element) //PRIVATE: returns the absolute Left value of element, in pixels
{
    var oNode = element;
    var iLeft = 0;

    while(oNode.tagName != 'BODY') {
        iLeft += oNode.offsetLeft;
        oNode = oNode.offsetParent;        
    }

    return iLeft;
};

More specifically, if i remove the actual while loops then the calendar will display OK, just that its positioning on the page is wrong?

EDIT

Code below which sets 'element'

<script type="text/javascript">

        window.onload = function() {
            var bas_cal, dp_cal, ms_cal;
            dp_cal = new Epoch('epoch_popup', 'popup', document.getElementById('<%=txtDateOfDiag.ClientID%>'));
            dp_cal = new Epoch('epoch_popup', 'popup', document.getElementById('<%=txtDOB.ClientID%>'));
        };

</script>

Note: I am using asp.net Master pages which is why there is a need for the .ClientID

EDIT

A further update - I have recreated this without applying css (but including the .js file provided by the designer) the code still works fine which, there must be some sort of conflict between the CSS and my JavaScript?

Answer 1

That would lead me to believe that the tagName does not match, possibly because you have it in upper case. You might try while(!oNode.tagName.match(/body/i)) {

Answer 2

what happens if you add a line of debug code like this:

var oNode = element;
var iLeft = 0;  
alert(oNode);

This might give different results in different browsers; I think it may be NULL for IE.
You may want to have a look at the code that provides the value of the 'element' parameter to see if there's a browser-dependant issue there.