JSFiddle - React, Tailwind, and code Playground

JavaScript

function CommaFormattedN(amount) {

    var delimiter = ","; 
    var i = parseInt(amount);
    
    if(isNaN(i)) { return ''; }
    
    var origi = i;  // store original to check sign
    i = Math.abs(i);
    
    var minus = '';
    if (origi < 0) { minus = '-'; } // sign based on original

    var n = new String(i);
    var a = [];

    while(n.length > 3)
    {
        var nn = n.substr(n.length-3);
        a.unshift(nn);
        n = n.substr(0,n.length-3);
    }

    if (n.length > 0) { a.unshift(n); }

    n = a.join(delimiter);

    amount = minus + n;

    return amount;

}

var number = 2341234;
alert(CommaFormattedN(number));