Question

How to check whether a cookie named, let’s say username exist?

I have to code Javascript code that will run when that cookie is not set.

Answer 1

This should help you get started:

function checkCookie(){
var username=getCookie("username");
  if (username!=null && username!="")
  {
    return true;
  }
  return false;
}


function getCookie(c_name){
var i,x,y,ARRcookies=document.cookie.split(";");
for (i=0;i<ARRcookies.length;i++)
{
  x=ARRcookies[i].substr(0,ARRcookies[i].indexOf("="));
  y=ARRcookies[i].substr(ARRcookies[i].indexOf("=")+1);
  x=x.replace(/^\s+|\s+$/g,"");
  if (x==c_name)
    {
    return unescape(y);
    }
  }
}