JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="formattedNumberField" value="" />

JavaScript

//jQuery
$("#formattedNumberField").on('keyup', function(evt){
    if (evt.which != 110 ){//not a fullstop
        var n = parseFloat($(this).val().replace(/\,/g,''),10);
        $(this).val(n.toLocaleString());
    }
});