document.getElementById(control).value not working with IE8

var tagID = document.getElementByn("<%=ddlSectionHeaderID%>").value;
var tagIndex = document.getElementById("<%=ddlSectionHeaderID%>").selectedIndex;
var tagName = document.getElementById("<%=ddlSectionHeaderID%>").children(tagIndex).innerText;
var exportI开发者_JAVA百科D = document.getElementById("<%=hdnExportID%>").value;

This gives me "Object doesn't support this property"

It would help to see the rendered output and what references resulted in the rendered script.

The "Object doesn't support this property" error means that you are trying to access a property that does not exist for that object. perhaps when this script is rendered, what you think should be a select element is actually a text input. If that is the case, the selectedIndex property wont exist (this is just one possibility - you will know more if you were able to see the resulting string).