JSFiddle - React, Tailwind, and code Playground

HTML

<span id="ninja_forms_field_83">
    87457
</span>

JavaScript

function numberWithCommas(x) {
    return x.toString().replace(/\B(?=(?:\d{3})+(?!\d))/g, ",");
}
    
v_pound = $('span#ninja_forms_field_83').html();
v_pound = numberWithCommas(v_pound);
$('span#ninja_forms_field_83').html(v_pound);