If you want to submit your form by click on link or by another Javascript action:
$('a#link_submit').click(function(event){
$('form#user').jsFormValidator('submitForm', event);
});
Pure Javascript:
var link = document.getElementById('link_submit');
link.addEventListener('click', function (event) {
var form = document.getElementById('user');
FpJsFormValidator.customize(form, 'submitForm', event);
});