js object used in js file not runat=server

 Ok I have learnt that if I have a object like this..(subject matter is transferring code from on aspx to js file)
<asp:label ID="mylabel" runat="server">Comments...</>
To reference in a file I must create a global variable on aspx/ascx and use that variable in JS code file.
Like this thread : http://forums.asp.net/t/1470450.aspx
QUESTION1: But what is the object DOES NOT have a runat server tag and its normal HTML with an ID..like
<img id ="imagSymbolSelected" src="../images2/Other_Question3.gif" visible="true" />   Do I have still have to create a global variable to reference it in JS file within  a js function. Of can I use it like this in the file . ...