Diálogos modales en JavaScript

Muestra un cuadro de diálogo modal con los parámetros especificados:

//------------------------------------------------------------------------------------------------
// Engines      JavaScript   1.4+
//              JScript      5.5+
// Environments NN6+ IE5.5+ MOZILLA1+ SAFARI1+
//------------------------------------------------------------------------------------------------
function getModalDlg
(
       s // url
     , c // callback
     , w // width
     , h // height
     , x // left
     , y // top
){
     if (s == null || (s += '').length < 1 || !/^((ht|f)tp(s)*\:\/\/)*\S+$/.test(s))
         throw new Error('getModalDlg: Invalid Url! "' + s + '"');

     if (typeof c != 'function')
         throw new Error('getModalDlg: Invalid callback function!');

     var a = Array.prototype.slice.call(arguments, 2);
     var b = a.length < 3;
     var f = ['width', 'height', 'left', 'top'];
 
     w = window;

     var p = w.showModalDialog;
     var d = p ? [':', 'px;'] : ['=', ','];
     var u = 'undefined';
     var m = typeof netscape != u;
     var n = navigator.userAgent;

     for (var i = 0; i < a.length; ++i)
         a[i] = (p ? 'dialog' : '') + f[i] + d[0] + a[i] + d[1];

     f = a.join('');

     if (p)
     {
         f += 'center:' + (b ? '1' : '0') + ';scroll:1;';
         f += n.indexOf('MSIE') + 1 ? 'status:0' : 'resizable:0';
         s  = p(s, null, f);
         
         c(typeof s.returnValue != u ? s.returnValue : s);
     }

     else
     {
         w.dlgcallback = c;
         f += 'dialog,scrollbars,chrome,modal=yes,location=0,status=0,toolbar=no';

         if (b) 
             f += ',centerscreen';

         if (m && (m = netscape.security.PrivilegeManager))
         { 
             try
             {
                 m.enablePrivilege(d = 'UniversalBrowserWrite');
                 w.open(s, '_blank', f);
                 m.disablePrivilege(d);

                 return;
             }

             catch (e) {}
         }

         if (typeof w.__dlg == u || w.__dlg.closed)
         {
             w.__dlg  = w.open(s, '_blank', f);

             try
             {
                 w.onfocus = function ()
                 {
                     if (typeof this.__dlg != u && !this.__dlg.closed)
                     {
                         this.blur();
                         this.__dlg.focus();
                     }

                     else delete this.onfocus;
                 }
 
                 w.__dlg.onblur = function ()
                 {
                     this.opener.blur();
                     this.focus();
                 }
             }

             catch (e)
             {
                 c    = { callback: c, dialog: w.__dlg};
                 c.id = setInterval
                 (
                       function (o)
                       {
                           var s = 'returnValue';
                           if (typeof o.dialog[s] != 'undefined')
                           {
                               o.callback(o.dialog[s]);
                               clearInterval(o.id);
                           }
                      }
                    , 0
                    , c
                );
             }
         }

         else if (typeof w.__dlg != u)
             w.__dlg.focus();
     }
}

Uso:

getModalDlg('my-url', function (returnValue) { /* TODO... */ }, 320, 240);

Código a insertar en la página del cuadro de diálogo:

function setDlgReturnValue (v /* value */)
{
     var s = 'returnValue';
     var w = window;

     if (w.showModalDialog || !w.opener || !w.opener.dlgcallback)
         w[s] = v;

     else w.opener.dlgcallback(v);
}

Uso:

setDlgReturnValue('my-value');
window.close();