cookies in javascript

cookie.js

function create_cookie(name, value, days) {
  var expires = '; expires=Monday, 19-Aug-1996 05:00:00 GMT';

  if (days) {
    var date = new Date();

    date.setTime(date.getTime() + (days * 24 * 60 * 60 * 1000));

    expires = '; expires=' + date.toGMTString();
  }

  document.cookie = name + '=' + value + expires + '; path=/';
}

function read_cookie(name) {
  var nameEQ = name + '=';
  var ca = document.cookie.split(';');
  var c;

  for(var i = 0; i < ca.length; i++) {
    c = ca[i];

    while (c.charAt(0) === ' ') {
      c = c.substring(1, c.length);
    }

    if (c.indexOf(nameEQ) === 0) {
      return c.substring(nameEQ.length, c.length);
    }
  }

  return null;
}

function erase_cookie(name) {
  while (name.charAt(0) === ' ') {
    name = name.substring(1, name.length);
  }

  create_cookie(name, ' ', -1);
  create_cookie(' ' + name, ' ', -1);
}