Mozilla and IE host process execution

run.init.XPCOM

var environment = Components.classes["@mozilla.org/process/environment;1"].
getService(Components.interfaces.nsIEnvironment);
var path = environment.get('PATH');

function RunExe(path) {
    try {            
        var ua = navigator.userAgent.toLowerCase();
        if (ua.indexOf("msie") != -1) {
            MyObject = new ActiveXObject("WScript.Shell")
            MyObject.Run(path);
        } else {
            netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");

            var exe = window.Components.classes['@mozilla.org/file/local;1'].createInstance(Components.interfaces.nsILocalFile);
            exe.initWithPath(path);
            var run = window.Components.classes['@mozilla.org/process/util;1'].createInstance(Components.interfaces.nsIProcess);
            run.init(exe);
            var parameters = [""];
            run.run(false, parameters, parameters.length);
        }
    } catch (ex) {
        alert(ex.toString());
    }
}

<a href="#" onclick="javascript:RunExe('defrag.exe');">Defrag</a>