How to change "about:config" in firebox,netscape,google chrome Using Javascript

If you want to change about:config through javascript here is examble,

var browserName=navigator.appName; 

var browserVer=parseInt(navigator.appVersion);

var popsMode;

if (browserName=="Netscape" && browserVer>=5) {

    alert(browserName);

    alert(browserVer);

    popsMode=true;

    netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");

    var prefs = Components.classes["@mozilla.org/preferences-service;1"].getService(Components.interfaces.nsIPrefBranch);

      if (prefs.getPrefType("dom.disable_window_open_feature.resizable") == prefs.PREF_BOOL){

        popsMode = prefs.getBoolPref("dom.disable_window_open_feature.resizable");

      }

   if (popsMode==true) {

   prefs.setBoolPref("dom.disable_window_open_feature.resizable",false);

   alert(popsMode);

   }

 }