JS - convert Title to Slug

file.html

<script>
// title to slug
function title_to_slug(title_id, slug_id)
{
    string = document.getElementById(title_id).value;
    string = string.toString().trim().toLowerCase()
        .replace(/\s+/g, "-")
        .replace(/[^\w\-]+/g, "")
        .replace(/[0-9]/g, "")
        .replace(/-that|-keyword|-need|-to|-remove|-from|-slug/gi, "")
        .replace(/\-\-+/g, "-")
        .replace(/^-+/, "")
        .replace(/-+$/, "")
    ;
    document.getElementById(slug_id).value = string;
}
</script>

<input onkeyup="title_to_slug('title', 'slug');" id="title" type="text">
<input id="slug" type="text">