Judgment before the file is uploaded

When the file is uploaded, if the drop-down list box or File box is empty, an error will be reported. Here, this problem is solved.

Extract a test of the value in the dropboard: Please give the drop-down value: ; function a () {window.confirm (Document.Mychoise.Options [Document .all.mychoise.selectedindex] .text);}

Here is a specific list box:

- Select phone model - <% ds = (dataset) Request.getattribute (EnumConstant. MachType); ds.first (); do {%> > <% = ds.getstring ("Mobile_name")%> <% } while (ds.next ()); string s;%>

Here is a File control:

Finally, it is judge that if it is empty, it does not work: