Check kind of selected channel using javascript

[milevic]

I try to create script which will check what is the kind of selected channel and based of that alert user, but i always got same message. Could someone help me with this code?

var myChannel = app.activeDocument.activeChannels;
if (myChannel.kind == "ChannelType.MASKEDAREA"||myChannel.kind  == "ChannelType.SELECTEDAREA"||myChannel.kind  == "ChannelType.SPOTCOLOR") {
alert("It is not CMYK")
}
else{
alert("It is CMYK")
}

[c.pfaffenbichler · Accepted solution]

The plural »activeChannels« should be a give-away. 

Try inserting 

alert (myChannel.constructor);

to see what myChannel actually is. 

[jazz-y · Accepted solution]

Yes, as rightly noted @c.pfaffenbichler  app.activeDocument.activeChannels is an array. It contains one or more elements (depending on the number of dedicated channels). That is, you need to either perform a check on all elements of this array in a loop, or (if you are sure that only one channel is selected) you can use it like this:

var myChannel = app.activeDocument.activeChannels.shift();

[milevic]

Thanks guys

[milevic]

Dear @c.pfaffenbichler @jazz-y is it possible somehow (with some if statement) to check is it currently selected one or multiply channels? THanks in advance

[c.pfaffenbichler]

Check whether the length of 

app.activeDocument.activeChannels

is equal to 1 with an if-clause.  

[milevic]

Thanks, i tried this and it works

var myActiveDoc = app.activeDocument;
var myChannels = myActiveDoc.activeChannels;
var total = myChannels.length;
if(total>1){   
    alert("multiply channels are selected")
}
else {
    alert("single channel is selected")
}

[milevic]

But now i stuck again, when i selected some mask which is applied on some adjustment layer (curves, channel mixer,..) and when i run this script i got an error. Is it possible to improve this?

[c.pfaffenbichler]

You could wrap the whole thing in a try-clause and in the catch alert that a Layer Mask is selected. 

To me at least no other reason comes to mind for activeChannels erroring, it seeems impossible to have 0 Channels selected in an open document. 

[milevic]

You are right, i resolved with try/catch clause, thanks for idea