You just figure out what "<%=date1OEDatePicker.ClientID%>" really is. At runtime, such statement is being pre-processed by ASP.NET first. It evaluates such statements and replaces them with the evaluated result, once it is evaluated, it is pure JavaScript and can be processed by your browser's JavaScript engine. When you want to take ASP.NET out of the equation by separating them into a JavaScript file, you got to do the evaluation by yourself. Usually people do not separate such small segment of JavaScript because the trouble outweighs the benefits.
If you have any more questions regarding this particular topic, you may wish to seek help from other resources. Our support don't mind giving you a few pointers as to where to look, but we generally don't cover through such issues as they are generic ASP.NET programming issues that are not really related to our product. You can find more detailed explanations of our support policy at here:
http://www.essentialobjects.com/Forum/Default.aspx?g=posts&t=1368Thanks