How dangerous is e.preventDefault();, and can it be replaced by keydown/mousedown tracking?
- by yc
I'm working on a tracking script for a fairly sophisticated CRM for tracking form actions in Google Analytics. I'm trying to balance the desire to track form actions accurately with the need to never prevent a form from not working.
Now, I know that doing something like this doesn't work.
$('form').submit(function(){
_gaq.push('_trackEvent', 'Form', 'Submit', $(this).attr('action'))
});
The DOM unloads before this has a chance to process.
So, a lot of sample code recommends something like this:
$('form').submit(function(e){
e.preventDefault();
var form = this;
_gaq.push('_trackEvent', 'Form', 'Submit', $(this).attr('action'));
//...do some other tracking stuff...
setTimeout(function(){
form.submit();
}, 400);
});
This is reliable in most cases, but it makes me nervous. What if something happens between e.preventDefault();and when I get around to triggering the DOM based submit? I've totally broken the form.
I've been poking around some other analytics implementations, and I've noticed something like this:
$('form').mousedown(function(){
_gaq.push('_trackEvent', 'Form', 'Submit', $(this).attr('action'));
});
$('form').keydown(function(e){
if(e.which===13) //if the keydown is the enter key
_gaq.push('_trackEvent', 'Form', 'Submit', $(this).attr('action'));
});
Basically, instead of interrupting the form submit, preempting it by assuming that if someone is mousing down or keying down on Enter, than that form is submitted. Obviously, this will result in a certain amount of false positives, but it completely eliminates use of e.preventDefault();, which in my mind eliminates the risk that I might ever prevent a form from successfully submitting.
So, my question:
Is it possible to take the standard
form tracking snippet and prevent it
from ever fully preventing the form
from submitting?
Is the
mousedown/keydown alternative viable?
Are there any submission cases it may miss? Specifically, are there other ways to end up submitting besides the mouse and the keyboard enter? And will the browser always have time to process javascript before beginning to unload the page?
