Check form to which fields have been filled in before a user abandons it and send the fields to Google Analytics.

google-analytics.js

// stuff to do before the page un loads
if ( $('[data-page-name="contact"]').length ) {
    var count = 0;
    window.onbeforeunload = function(e) {
        var contactUsForm = $('[data-page-name="contact"]').find('.contact-us-form');
        var requiredFields = contactUsForm.find('[data-val-required]');

        var completedFields = [];
        var missedFields = [];
        
        $.each(requiredFields , function(index, formField) {

            if ( $(formField).is('input[type=text]') || $(formField).is('textarea') ) {
                if ($(formField).val() !== '') {
                    completedFields.push( $(formField).siblings('label').text().trim() );
                }
                else {
                    missedFields.push( $(formField).siblings('label').text().trim() );
                }
            }
            else if ( $(formField).is('select') ) {
                if ($(formField).val() !== '') {
                    completedFields.push( $(formField).parent().siblings('label').text().trim() );
                }
                else {
                    missedFields.push( $(formField).parent().siblings('label').text().trim() );
                }
            }
        });

        if (completedFields.length !== requiredFields.length) {

            var flattenedCompletedFields = completedFields.toString();
            var flattenedMissingFields = missedFields.toString();
            
            _self.trackThisBounceRateCalculationUnaffected({
                category:'Contact',
                action: 'Abandoned',
                label: 'Completed fields: ' + (completedFields.length === 0 ? 'None' : flattenedCompletedFields) + '. Missing fields: ' + flattenedMissingFields
            });
            
            return false;                 
        }
    };
}