JSFiddle - React, Tailwind, and code Playground

by Zsanett Tamás

HTML

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

JavaScript

var num = document.getElementbyId("num");
num = addCommas(num);
alert(num);

function addCommas(nStr) {
    nStr += '';
    x = nStr.split('.');
    x1 = x[0];
    x2 = x.length > 1 ? '.' + x[1] : '';
    var rgx = /(\d+)(\d{3})/;
    while (rgx.test(x1)) {
            x1 = x1.replace(rgx, '$1' + ',' + '$2');
    }
    return x1 + x2;
}