How to prevent browsers from retrying failed POST requests (and check for internet connectivity)?

I have a site intended for mobile users that would check the connectivity for every POST requests. If there is no internet connectivity, I will prompt our an error message for to user. Also, I would like to have a transition effect indicating the form is being submitted. I have the following codes

var progress = 0;

 $('div').on('submit', 'form', function(e){

     var thisform = this;        

     if(progress === 1){             

        // check internet connection     
        var connection = hostReachable();                           

        if(!connection){        
            alert('No connection');
            setTimeout(function(){ // re-allow submission after 8000 ms (not immediately to avoid browser retry)
                progress = 0;
            },8000);    
            return false;
        }   

         return true;            
     }

     e.preventDefault();
     e.stopPropagation();

     if(progress === 0){ // first submit

        // updated progress value            
        progress = 1;           

        //form transition               
        $('.spinner').show('fast', function(){
            $('.pagecontent').fadeOut('fast');      
            thisform.submit();
        });

     } else {
         // prevent submit retries when no connectivity
         return false;           
     }
 });

where hostReachable() is a function for checking connectivity using xhr request.

The problem is now after the thisform.submit(); the form submission event seems not triggered again. So the codes inside if(progress === 1) is never run. Why is it so? What's wrong with my codes? Thanks!