JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="num">

JavaScript

$(document).ready(function(){    
    $("#num").blur(function(){
        $(this).val(formatNumber($(this).val()));
    });
});


function formatNumber (num) {
    return num.toString().replace(/(\d)(?=(\d{3})+(?!\d))/g, "$1'")
}