How to check whether file exist in the queue to Upload or not

Hi all,
I am using ajax toolkit file upload control and on click of my submit button i need to check whether the file selected by the user is uploaded or not and give a error message if not.
 
I tried a way that once the file is selected by user then upload button visibility is coming ,by that way i done that.but now i found if user select the file and removed that.at this point also the upload button is coming .So my validation got failed.
 
Now i thought of getting the queue container and loop through each and every child elements and match with the remove button in that particular div.
 
please tell me that ,what am i doing is right? and suggest me the way to achieve this.