JSFiddle - React, Tailwind, and code Playground

by Otobong Okoko

HTML

<input class="number">

JavaScript

$(document).ready(function(){
  $('input.number').keyup(function(event){
      // skip for arrow keys
      if(event.which >= 37 && event.which <= 40){
          event.preventDefault();
      }
      var $this = $(this);
      var num = $this.val().replace(/,/gi, "").split("").reverse().join("");
      
      var num2 = RemoveRougeChar(num.replace(/(.{3})/g,"$1,").split("").reverse().join(""));
      
      console.log(num2);
      
      
      // the following line has been simplified. Revision history contains original.
      $this.val(num2);
  });
});

function RemoveRougeChar(convertString){
    
    
    if(convertString.substring(0,1) == ","){
        
        return convertString.substring(1, convertString.length)            
        
    }
    return convertString;
    
}