adding some classic .asp code to javascript

What is the problem.  What you have is correct.  However, keep in mind javascript runs AFTER the page loads and asp runs on the server BEFORE the page loads.  

Also you have <%=rs(width")%>  and it should be <%=rs("width")%> (missing quote)

if I have it like this the slider stops working:

slider1.$SetScaleWidth(Math.min(parentWidth, <%=rs("width")%> ));

if I have it like this the slider will work but it isn't pulling the value from the db:
slider1.$SetScaleWidth(Math.min(parentWidth, '<%=rs(width")%>' ));

You just added a complete new variable with single quotes.

slider1.$SetScaleWidth(Math.min(parentWidth, <%=rs("width")%> ));

if I have it like this the slider will work but it isn't pulling the value from the db:
slider1.$SetScaleWidth(Math.min(parentWidth, '<%=rs(width")%>' ));

IF it worked without single quotes, why are you adding?  My comment was about the double quotes missing for the field name, width.

Try no single quotes and double quotes for the field name.  Also, view source and make sure there is actual data for  <%=rs("width")%>  

slider1.$SetScaleWidth(Math.min(parentWidth, <%=rs("width")%> ));

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I understand that .. what I am saying is it isn't pulling the data for the size when using slider1.$SetScaleWidth(Math.min(parentWidth, <%=rs("width")%> )); and the slider stops working.

Does this work?

slider1.$SetScaleWidth(Math.min(parentWidth, 1040 ));

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If it does, check if this works

slider1.$SetScaleWidth(Math.min(parentWidth, <%="1040"%> ));

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If that works, see if this works

<%
dim myWidth
myWidth="1040"
%>
slider1.$SetScaleWidth(Math.min(parentWidth, <%=myWidth%> ));

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If all this works and the below does not, then you need to check that there is data in the rs("width")

slider1.$SetScaleWidth(Math.min(parentWidth, <%=rs("width")%> ));

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One way you can do this is add the code just before the js you have and write out the width and add a response.end.  This will render the page and end it just after it spits out the width.  

response.write "The width is set to: "& rs("width")
response.end

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It is possible the data looks good visually, but may have a character you can't see or space. Try this.

if not isnull(rs("width")) then
     if isnumeric(rs("width") then
         response.write "The width is set to: "& rs("width")
         else
         response.write "There is data in the width, but it is not numeric"
     end if
    else
    response.write "The field is null"
end if
response.end

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Is this the sample you are working off of? https://github.com/jssor/slider.js/blob/master/themes-jquery/image-slider.source.html

function ScaleSlider() {
                var parentWidth = jssor_slider1.$Elmt.parentNode.clientWidth;
                if (parentWidth)
                    jssor_slider1.$SetScaleWidth(Math.min(parentWidth, 600));
                else
                    window.setTimeout(ScaleSlider, 30);
            }

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If it is, why are you trying to set the width dynamically.  If you have 10 images listed, they are all going to be the same size or at least in the same size container. Unless for every page refresh (request.querystring or request.form) you are using a different layout that requires the parent to use a different width for the set of images, I think this should be static.

If I have this wrong, your next step here should be to render your html (run the page so it is working), view source, then paste that code here so we can see how you are using it.  Then let us know which parts should be dynamic and how you are getting the data.

I think rs("width") is not returning the value that you are expecting. Perhaps you have some issue with the code used to retrieve data. Open your page in a web browser, right click and then select View Page Source. In the page source, look at your javascript line and you will see the issue.

I repeat it again that most probably rs("width") is not returning the value that you are expecting.

Thanks for the help