Prevent multiple clicks and submissions in Contact Form 7

blockClicks.js

//http://epsiloncool.ru/programmirovanie/preventing-multiple-submits-in-contact-form-7
jQuery(document).on('click', '.wpcf7-submit', function(e){
     if( jQuery('.ajax-loader').hasClass('is-active') ) {
          e.preventDefault();
          return false;
     }
});