Set opacity of particular layer

[boo_radley_2013]

Hi, I have a layer named 'concrete' and I'm trying to adjust its opacity to 50% in a script. Problem is, this script adjusts the active layer's opacity, not the layer named 'concrete'. So in other words the active layer might be 'Layer 12', and somewhere else in the layer stack is the layer named 'concrete'. I want to adjust its opacity to 50% without having to switch over to the 'concrete' layer, manually adjust the opacity, and then switch back to 'layer 12'. I was hoping a script could just change it automatically.  Here's what I have so far, I'm hoping someone might suggest a tweak to get it working:

#target photoshop

var layerRef = app.activeDocument.layers.getByName( 'concrete' );


// =======================================================
var idsetd = charIDToTypeID( "setd" );
    var desc9657 = new ActionDescriptor();
    var idnull = charIDToTypeID( "null" );
        var ref2889 = new ActionReference();
        var idLyr = app.activeDocument.layers.getByName( 'concrete texture' )( "Lyr " );
        var idOrdn = charIDToTypeID( "Ordn" );
        var idTrgt = charIDToTypeID( "Trgt" );
        ref2889.putEnumerated( idLyr, idOrdn, idTrgt );
    desc9657.putReference( idnull, ref2889 );
    var idT = charIDToTypeID( "T   " );
        var desc9658 = new ActionDescriptor();
        var idOpct = charIDToTypeID( "Opct" );
        var idPrc = charIDToTypeID( "#Prc" );
        desc9658.putUnitDouble( idOpct, idPrc, 50.000000 );
    var idLyr = charIDToTypeID( "Lyr " );
    desc9657.putObject( idT, idLyr, desc9658 );
executeAction( idsetd, desc9657, DialogModes.NO );

[c.pfaffenbichler · Accepted solution]

You seem to mix DOM and AM code.

A simple

app.activeDocument.layers.getByName( 'concrete' ).opacity  = 50;

should suffice if the Layer named "concrete" is at the top-level and not in a group.

[boo_radley_2013]

wow, thanks - I had no idea it was that easy. How about if the 'concrete' layer was indeed inside a group - does it make things more complicated?