how to fire javascript code when button is submit pressed

i have a wordpress contact form with contact form 7 and need to fire javascript when submit button is pressed. how can i do this? what to add in footer ?

 

Use an ID on the submit, and trigger the javascript when that is clicked? If you're using jQuery (most libraries are built in to Wordpress, and can be called on), it would be something like:

$('#submit_button_id').click(function() {
// do stuff here
});

Code (markup):

That assumes you have jQuery loaded