PHP and Javascript code needed to check if form fields are not empty

Question

Javascript needed to prevent form submit if any of field is empty. all my form fields start names start with name=add[FieldName] those are the fields that need checking.

PHP, backend check before submiting to database double check to make sure all $POST are not empty

Answer 1

I'm not going to write the javascript, but here's some PHP.

$valid = true;
foreach($_POST as $key)
{
    if(!isset($key))
    {
        $valid = false;
    }
}

if(!$valid)
{
    header("Location: /path/to/form");
}

Answer 2

Here's a javascript function you can use. Just call it for each id belonging to the fields in question.

function isEmpty(field_id) {
  var empty = false;
  if (document.getElementById(field_id).value == null)
    empty = true;

  if (document.getElementById(field_id).value == "")
    empty = true;

  return empty;
}

If you have them predictably named, you could call this function in a loop. If, for instance, they were named field1, field2, ..., field23, then you could just have the following in your main code body:

for (i = 0; i < 24; i++) {
    var emptyCheck = false;
    if(isEmpty("field"+i)) {
        emptyCheck = true;
        //do whatever you want to do when a value is empty
    }
}