Javascript works on IE but not on Firefox and gives me error as Error: cprofiledetailscollapse is not defined

I use C#.net. I wrote JavaScript for hide and show expand and collapse div accordingly. It work well in IE but not on Firefox, not even call the JavaScript function and gives me error as Error: ctl00_cpContents_dlSearchList_ctl08_profiledetailscollapse is not defined. My JavaScript is as follows

function displayDiv(divCompact, divExpand) {
        //alert('1');
            var str = "ctl00_cpContents_";
            var divstyle = new String();
//            alert("ibtnShowHide" + ibtnShowHide);
            divstyle = divCompact.style.display;
            if (divstyle.toLowerCase() == "block" || divstyle == "") {
                divCompact.style.display = "开发者_如何学Cnone";
                divExpand.style.display = "block";
//                ibtnShowHide.ImageUrl = "images/expand_img.GIF";
            }
            else {
//                ibtnShowHide.ImageUrl = "images/restore_img.GIF";
                divCompact.style.display = "block";
                divExpand.style.display = "none";
            }
            return false;
        }

---

ctl00_cpContents_dlSearchList_ctl08_profiledetailscollapse is an element id generated by ASP.NET. It's a profiledetailscollapse control inside dlSearchList.

JavaScript variable "ctl00_cpContents_dlSearchList_ctl08_profiledetailscollapse" is not defined. Firefox does not automatically create, for each element with an id, a variable in the global scope named after that id and containing a reference to the element.

You might want to consider using jQuery to make sure that your DOM manipulation is cross-browser compatible.