InDesign copy layer to another document - scripting

Question

I am trying to write a script that copies a layer from one document into another.
var srcDocName = 0;
var destDocName = 1;
var layerNameOriginal = "Original";
var layerNameCopyTo = "Destination";
var destDoc = app.documents.item(destDocName);
var layerSrc = app.documents.item(srcDocName).layers.item(layerNameOriginal);
try {
layerSrc.duplicate(destDoc, ElementPlacement.INSIDE);
}
catch(e) {
alert(e)
}
Apparently this works in Photoshop but not in InDesign. I have been trying for ages to find some decent documentation for InDesign scripting. But all I can find is the CS scripting guide, which isn't of much use.
http://wwwimages.adobe.com/www.adobe.com/content/dam/Adobe/en/products/indesign/pdfs/InDesignCS5_ScriptingGuide_JS.pdf
If someone can point me to a good reference to the object model I would be grateful.

Answer 1

After some more googling I finally found the answer:
var sourceLayer = app.documents[0].layers.itemByName("Layer1");
var destLayer = app.documents[1].layers[0];
sourceLayer.pageItems.everyItem().duplicate(destLayer);
I also came across jongware which seems to be a complete Object reference extracted directly out of Adobe CS.

Answer 2

You can use this script: https://redokun.com/blog/indesign-copy-entire-layer-one-file-another
The underlying implementation is basically the same, but we've added a UI so it's not necessary to edit the script every time the layer name changes.
Edit: We've been told that the solution above doesn't work with threaded text frames, so I re-wrote the script. The new implementation is way more complex but it now supports threaded TFs.

Answer 3

To expand on the solution offered by Loopo and offer you the ability to copy all layers from 1 document to another...
main();
function main()
{
var source = GetSourceDocument();
if(source == -1)
{
return;
}
var target = GetTargetDocument ();
if(target == -1)
{
return;
}
if(target == source)
{
return;
}
copyLayersOver(source, target);
}
function GetSourceDocument()
{
var returnVal = -1;
var oldPrefs = app.scriptPreferences.userInteractionLevel;
app.scriptPreferences.userInteractionLevel=UserInteractionLevels.INTERACT_WITH_ALL;
var dialog = app.dialogs.add({name:"Document to Copy From", canCanel: true, label:"DocumentToCopyFrom"});
var col1 = dialog.dialogColumns.add();
var StringList= [];
for(var i = 0; i<app.documents.length; i++)
{
StringList.push("[" + app.documents[i].index + "] " + app.documents[i].name);
}
var ddl = col1.dropdowns.add({id:"SourceDocDDL", stringList: StringList});
if(dialog.show() == true)
{
returnVal = ddl.stringList[ddl.selectedIndex].split("]")[0].substr(1);
}
else
{
returnVal -1;
}
dialog.destroy();
app.scriptPreferences.userInteractionLevel = oldPrefs;
return returnVal;
}
function GetTargetDocument()
{
var returnVal = -1;
var oldPrefs = app.scriptPreferences.userInteractionLevel;
app.scriptPreferences.userInteractionLevel=UserInteractionLevels.INTERACT_WITH_ALL;
var dialog = app.dialogs.add({name:"Document to Copy To", canCanel: true, label:"DocumentToCopyTo"});
var col1 = dialog.dialogColumns.add();
var StringList= [];
for(var i = 0; i<app.documents.length; i++)
{
StringList.push("[" + app.documents[i].index + "] " + app.documents[i].name);
}
var ddl = col1.dropdowns.add({id:"SourceDocDDL", stringList: StringList});
if(dialog.show() == true)
{
returnVal = ddl.stringList[ddl.selectedIndex].split("]")[0].substr(1);
}
else
{
returnVal -1;
}
dialog.destroy();
app.scriptPreferences.userInteractionLevel = oldPrefs;
return returnVal;
}
function copyLayersOver(source, target)
{
var sourceDocument = app.documents[source];
var targetDocument = app.documents[target];
var sourceLayers = sourceDocument.layers;
//Match the number of pages
while(targetDocument.pages.length < sourceDocument.pages.length)
{
targetDocument.pages.add();
}
//copy the layers over
for(var i= 0; i < sourceLayers.length; i++)
{
var names = targetDocument.layers.everyItem().name;
var merge = false;
for(var y = 0; y < names.length; y++)
{
if(names[y] == sourceLayers[i].name)
{
merge = true;
break;
}
}
if(merge)
{
var targetLayer = targetDocument.layers.add();
targetLayer.name = "temp";
sourceLayers[i].pageItems.everyItem().duplicate(targetLayer);
targetDocument.layers.itemByName(sourceLayers[i].name).merge(targetLayer);
}
else
{
var targetLayer = targetDocument.layers.add();
targetLayer.name = sourceLayers[i].name;
targetLayer.layerColor = sourceLayers[i].layerColor;
sourceLayers[i].pageItems.everyItem().duplicate(targetLayer);
}
}
}