javascript dynamic variable syntax in loop

[chelnov63]

hi everyone my javascript code is: the form file input fields which are submitted are image_source1, image_source2, image_source3, ........ and so on (this number is dynamic) ..im not sure how to target these name dynamically

 

function validate_form()
{
  var counter = <?php echo $noImages ?>;
  var index = 0;
  
  for(var i = 1; i<= counter; i++)
  {
  if(form1.image_source[i].value.length == 0 )  //not sure of the correct syntax here
  {
    index++;
  }
  }
  
  if(index == counter) return false;
  else return true;
  
}

 

thanks in advance for your help

 

[chelnov63]

its ok i think ive got it:

 

if(form1["image_source"+i].value.length == 0 )