Disposal method for exportforweb animated gif

This is set in the timeline, before calling save for web to produce the animated GIF…

var idsetd = charIDToTypeID( "setd" );
    var desc44 = new ActionDescriptor();
    var idnull = charIDToTypeID( "null" );
        var ref6 = new ActionReference();
        var idanimationFrameClass = stringIDToTypeID( "animationFrameClass" );
        var idOrdn = charIDToTypeID( "Ordn" );
        var idTrgt = charIDToTypeID( "Trgt" );
        ref6.putEnumerated( idanimationFrameClass, idOrdn, idTrgt );
    desc44.putReference( idnull, ref6 );
    var idT = charIDToTypeID( "T   " );
        var desc45 = new ActionDescriptor();
        var idanimationFrameReplace = stringIDToTypeID( "animationFrameReplace" );
        var idanimationFrameReplaceType = stringIDToTypeID( "animationFrameReplaceType" );
        var idanimationFrameReplaceDontDispose = stringIDToTypeID( "animationFrameReplaceDontDispose" );
        desc45.putEnumerated( idanimationFrameReplace, idanimationFrameReplaceType, idanimationFrameReplaceDontDispose ); // 3rd parameter
    var idanimationFrameClass = stringIDToTypeID( "animationFrameClass" );
    desc44.putObject( idT, idanimationFrameClass, desc45 );
executeAction( idsetd, desc44, DialogModes.NO );

var idsetd = charIDToTypeID( "setd" );
    var desc51 = new ActionDescriptor();
    var idnull = charIDToTypeID( "null" );
        var ref7 = new ActionReference();
        var idanimationFrameClass = stringIDToTypeID( "animationFrameClass" );
        var idOrdn = charIDToTypeID( "Ordn" );
        var idTrgt = charIDToTypeID( "Trgt" );
        ref7.putEnumerated( idanimationFrameClass, idOrdn, idTrgt );
    desc51.putReference( idnull, ref7 );
    var idT = charIDToTypeID( "T   " );
        var desc52 = new ActionDescriptor();
        var idanimationFrameReplace = stringIDToTypeID( "animationFrameReplace" );
        var idanimationFrameReplaceType = stringIDToTypeID( "animationFrameReplaceType" );
        var idanimationFrameReplaceDispose = stringIDToTypeID( "animationFrameReplaceDispose" );
        desc52.putEnumerated( idanimationFrameReplace, idanimationFrameReplaceType, idanimationFrameReplaceDispose ); // 3rd parameter
    var idanimationFrameClass = stringIDToTypeID( "animationFrameClass" );
    desc51.putObject( idT, idanimationFrameClass, desc52 );
executeAction( idsetd, desc51, DialogModes.NO );