WPForms prevent duplicate / double form entry submissions

how-to.txt

<script type="text/javascript">
/**
 * Prevent double entry submissions.
 * 
 * Steps to install:
 * ​1 - Download and activate the "Insert Headers and Footers" plugin (by WPBeginner)
 * 2 - Go to Settings > Insert Headers and Footers
 * 3 - Paste this entire code snippet
 * 4 - Save
 */
jQuery(function($){
	$('.wpforms-form').on('submit',function(e){
		var $form     = $(this),
			validator = $form.validate(),
			valid     = validator.form();
		if (valid) {
			if ($form.data('submitted') === true) {
				// Previously submitted - don't submit again
				alert('Form already submitted. Please wait.');
				e.preventDefault();
			} else {
				// Mark it so that the next submit can be ignored
				$form.data('submitted', true);
				$form.find(':submit').text('Sending...');
			}			
		}
	});
});
</script>

Thank you!