phpjs/workbench/session/session_destroy.js

php.js offers community built php functions in javascript

function session_destroy() {
  // http://kevin.vanzonneveld.net
  // +   original by: Louis Stowasser
  // +   improved by: Brett Zamir (http://brett-zamir.me)
  // -    depends on: urlencode
  // *     example 1:
  // *     returns 1:

  var t = this;

  //* Bundle all session destroying functions (they all do the same thing)
  //* Resets the global $_SESSION and sets the cookie to null
  var session_set_cookie = function(name, value, expires, path, domain, secure) {
    if (expires) {
      expires = (new Date((new Date).getTime() + expires * 3600)).toGMTString();
    }

    var r = [name + '=' + t.urlencode(value)], s = {}, i = '';
    s = {expires: expires, path: path, domain: domain};
    for (var i in s) {
      if (s.hasOwnProperty(i)) { // Exclude items on Object.prototype
        s[i] && r.push(i + '=' + s[i]);
      }
    }

    return secure && r.push('secure'), document.cookie = r.join(';'), true;
  };

  t.$_SESSION = null;
	// t.setcookie('JSSESSID', null);
  return session_set_cookie('JSSESSID', null);
}