custom-change-last-word.js

<script>
    $(document).ready(function() {
        $('.js-title').each(function(index, element) {
            var heading = $(element);
            var word_array, last_word, first_part;
        
            word_array = heading.html().split(/\s+/); // split on spaces
            last_word = word_array.pop();             // pop the last word
            first_part = word_array.join(' ');        // rejoin the first words together
        
            heading.html([first_part, ' <span class="last-word">', last_word, '</span>'].join(''));
        });
    });
</script>