Originally Posted by Soptareanu @Alex
Where do I find what trigger the submit form on checkout page ? I saw that when i change some input value on the checkout, the form is submited. What .js action put this behavior on my form elements ?? I look on checkout\steps\shipping\parts\address.js but i don't understand how does it works !?
You found the right JS file. CheckoutAddressView.prototype.saveForm method is what you are looking for. See, there are calls of jQuery(form).submit() method. They actually submit the form.
I am not sure how helpful my answer is, so please let me know what you are trying to add/change, so I could better understand your task and suggest more meaningful actions.