To process all layer you need to use recursion. And layer names in a document need not be unique you can have many layers with the same name.
I played around once with a script to look at document layers to get a little better understand as to how Photoshop works.
// A Photoshop Script by JJMack's
// This script processes ArtLayers.
// This script is supplied as is. It is provided as freeware.
// The author accepts no liability for any problems arising from its use.
/*
<javascriptresource>
<about>$$$/JavaScripts/processArtLayers/About=JJMack's Process All Layers.^r^rCopyright 2009 Mouseprints.^r^rScript utility for action.^rNOTE:Deletes Seleted Area from background and all normal layers.</about>
</javascriptresource>
*/
//<category>JJMack's Script</category>
// enable double-clicking from Mac Finder or Windows Explorer
#target photoshop // this command only works in Photoshop CS2 and higher
// bring application forward for double-click events
app.bringToFront();
// ensure at least one document open
if (!documents.length) {
alert('There are no documents open.', 'No Document');
}
// if at least one document exists, then proceed
else {
app.activeDocument.suspendHistory('processArtLayers','main()');
}
///////////////////////////////////////////////////////////////////////////////
// main - main function
///////////////////////////////////////////////////////////////////////////////
function main() {
// declare local variables
var saveactiveLayer = activeDocument.activeLayer;
// Set the ruler units to PIXELS
var orig_ruler_units = app.preferences.rulerUnits;
app.preferences.rulerUnits = Units.PIXELS;
try {
processArtLayers(activeDocument);
removeAllEmptyLayerSets(activeDocument);
}
// display error message if something goes wrong
catch(e) { alert(e + ': on line ' + e.line, 'Script Error', true); }
try { activeDocument.activeLayer = saveactiveLayer;}
catch(e) { } // may have been deleted
// Reset units to original settings
app.preferences.rulerUnits = orig_ruler_units;
}
///////////////////////////////////////////////////////////////////////////////
// End - main function
///////////////////////////////////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////
// Function: processsArtLayers
// Input: document or layer set
// Return: <none>, all layers that were invisible are now gone
///////////////////////////////////////////////////////////////////////////////
function processArtLayers(obj) {
for( var i = obj.artLayers.length-1; 0 <= i; i--) {
try {
processLayer(obj.artLayers[i]);
}
catch (e) {
}
}
for( var i = obj.layerSets.length-1; 0 <= i; i--) {
infoLayer(obj.layerSets[i]); // Display layerSet informarion
processArtLayers(obj.layerSets[i]);
}
}
///////////////////////////////////////////////////////////////////////////////
// Function: removeAllEmptyLayerSets
// Usage: find all empty layer sets and remove them, recursively
// Input: document or layer set
// Return: empty layer sets are now gone
///////////////////////////////////////////////////////////////////////////////
function removeAllEmptyLayerSets(obj) {
var foundEmpty = true;
for( var i = obj.layerSets.length-1; 0 <= i; i--) {
if( removeAllEmptyLayerSets(obj.layerSets[i])) {
obj.layerSets[i].remove();
} else {
foundEmpty = false;
}
}
if (obj.artLayers.length > 0) {
foundEmpty = false;
}
return foundEmpty;
}
function processLayer(layer) {
infoLayer(layer);
}
function infoLayer(layer){
try{
alert("layer = " + layer
+ "\rallLocked = " + layer.allLocked
+ "\rblendMode = " + layer.blendMode
+ "\rbounds = " + layer.bounds
+ "\rfillOpacity = " + layer.fillOpacity
// + "\rfilterMaskDensity = " + layer.filterMaskDensity // undefined for groups not valid others ??
// + "\rfilterMaskFather = " + layer.filterMaskFeather // undefined for groups not valid others ??
+ "\rgrouped = " + layer.grouped
+ "\risBackgroundLayer = " + layer.isBackgroundLayer
+ "\rkind = " + layer.kind
+ "\rlayerMaskDensity = " + layer.layerMaskDensity
+ "\rlayerMaskFeather = " + layer.layerMaskFeather
+ "\rlinkedLayers = " + layer.linkedLayers
+ "\rname = " + layer.name
+ "\ropacity = " + layer.opacity
+ "\rparent = " + layer.parent
+ "\rpixelsLocked = " + layer.pixelsLocked
+ "\rpositionLocked = " + layer.positionLocked
// + "\rtextItem = " + layer.textItem // Valid only when kind = LayerKind.TEXT.
+ "\rtransparentPixelsLocked = " + layer.transparentPixelsLocked
+ "\rtypename = " + layer.typename
+ "\rvectorMaskDensity = " + layer.vectorMaskDensity
+ "\rvectorMaskFeather = " + layer.vectorMaskFeather
+ "\rvisible = " + layer.visible
+ "\rxmpMetadata = " + layer.xmpMetadata
);
}
catch(e){
}
};
/*
allLocked * boolean read-write. true to completely lock the contents and settings of this layer.
blendMode * blendmode read-write. the blending mode.
bounds * array of unitvalue read-only. an array of coordinates that describes the bounding rectangle of the layer.
fillOpacity * number [0.0..100] read-write. the interior opacity of the layer, a percentage value.
filterMaskDensity double read-write. the density of the filter mask (between 0.0 and 250.0)
filterMaskFeather double read-write. the feather of the filter mask (between 0.0 and 250.0)
grouped * boolean read-write. true if this layer is grouped with the layer beneath it.
isBackgroundLayer * boolean read-write. true if this is the background layer of the document. a document can have only one background layer. if there is no background layer,
setting this to true causes this to become the background layer.
kind * layerkind read-write. sets the type (such as 'text layer') for an empty layer. valid only when the layer is empty and when isbackgroundlayer.
you can use the kind property to make a background layer a normal layer; however, to make a layer a background layer, you must set isbackgroundlayer to true.
layerMaskDensity * double read-write. the density of the layer mask (between 0.0 and 100.0)
layerMaskFeather * double read-write. the feather of the layer mask (between 0.0 and 250.0)
linkedlayers * array of artlayer or layerset read-only. the layers linked to this layer. see artlayer.link.
name * string read-write. the name.
opacity * number [0.0..100.0]. read-write. the master opacity of the layer, a percentage value.
parent * document read-only. the object's container.
pixelsLocked * boolean read-write. true if the pixels in the layer’s image cannot be edited using the paintbrush tool.
positionLocked * boolean read-write. true if the pixels in the layer’s image cannot be moved within the layer.
textitem textitem read-only. the text item that is associated with the layer. valid only when kind = layerkind.text.
transparentpixelslocked * boolean read-write. true if editing is confined to the opaque portions of the layer.
typename * string read-only. the class name of the referenced artlayer object.
vectorMaskDensity * double read-write. the density of the vector mask (between 0.0 and 250.0)
vectorMaskFeather * double read-write. the feather of the vector mask (between 0.0 and 250.0)
visible * boolean read-write. true if the layer is visible.
xmpMetadata * xmpmetadata read-write. metadata for the layerb
*/
