Prevent Parsley double submitting when using javascript to initializing

prevent-parsley-double-submitting.md

click submit form A, form is valid: form A trigger submit event (1st time) --> form:submit event will be triggered --> Parsley make form A submit again (2rd time).

window.Parsley.on('form:submit', function (instance) {
    instance.submitEvent.preventDefault();
    return false;
});