jsx: How can I get a delay value of timeline frame ?

I understand the way to set delay value of timeline frame using Script Listener.

for example: Delay value is set as 0.1.

var idsetd = charIDToTypeID( "setd" );    var desc5 = new ActionDescriptor();    var idnull = charIDToTypeID( "null" );        var ref1 = new ActionReference();        var idanimationFrameClass = stringIDToTypeID( "animationFrameClass" );        var idOrdn = charIDToTypeID( "Ordn" );        var idTrgt = charIDToTypeID( "Trgt" );        ref1.putEnumerated( idanimationFrameClass, idOrdn, idTrgt );    desc5.putReference( idnull, ref1 );    var idT = charIDToTypeID( "T   " );        var desc6 = new ActionDescriptor();        var idanimationFrameDelay = stringIDToTypeID( "animationFrameDelay" );        desc6.putDouble( idanimationFrameDelay, 0.100000 );    var idanimationFrameClass = stringIDToTypeID( "animationFrameClass" );    desc5.putObject( idT, idanimationFrameClass, desc6 );
executeAction( idsetd, desc5, DialogModes.NO );

But I don't understand the way to get delay value of timeline frame. I think "animationFrameDelay" value should be gotten, how should scripting be written?