Deleting Channels

[Muppet_Mark-QAl63s]

Again another question on best methods/practices using JavaScript. In AppleScript I can do this (my filter again):

delete (every channel whose kind is not component channel)

In JavaScript would I be best served by checking the mode (know how many channels I should have) and remove the rest? Loop through all using if else on ChannelType.SELECTEDAREA etc. Also Im thinking all the channels will be at the end so is a reversed loop possible? What I have been tinkering with so far is this:

var docRef = app.activeDocument;

var docMode = docRef.mode;

var docChannels = docRef.channels;

var chanCount = docRef.channels.length;

if (chanCount > 3) {

alert(chanCount);

for ( var i = 0; i < chanCount; i++ ) {

    if( docChannels.kind == ChannelType.MASKEDAREA ){

        alert("MA channel");

        // I will remove this

        }

    if( docChannels.kind == ChannelType.SELECTEDAREA ){

        alert("SA channel");

        // I will remove this

        }

    if( docChannels.kind == ChannelType.SPOTCOLOR ){

        alert("SC channel");

        // I will merge this

     }

     }

     }

can I use something like this ( var i = chanCount; i = 0; i-- ) or have I overlooked something completely?

[Muppet_Mark-QAl63s]

OK, I tried this and it looks like I can reverse loop with this:

var chanCount = 6

for ( var i = chanCount; i > 0; i-- ) {

        alert(i);

     }

But Im sure I need to fix using somethings.length so the zero based thing works Im I correct?

[xbytor2 · Accepted solution]

for ( var i = docChannels.length-1; i >= 0; i-- ) {

var channel = docChannels+;

//...

}

[Muppet_Mark-QAl63s]

I had tried using "=" and using ">" not the ">=" operator…

Can I also take it that I can also change the "--" or "++" shorthands to say "+ 3" and jump?

[xbytor2]

Can I also take it that I can also change the "--" or "++"

i++;

is the same as

i += 1;

is the same as

i = i + 1;

shorthands to say "+ 3" and jump?

You've lost me here.

[Michael_L_Hale]

If by jump you mean step

i += 3

or

i = i + 3

would step 3

[Muppet_Mark-QAl63s]

Yep thats what I meant but did not explain very clearly…

What I managed to work out was the last one in both yours & x's posts

var chanCount = 15

for ( var i = chanCount; i >= 0; i = i - 3 ) {

        alert(i);

     }

so cool