Break out of loop on demand - by button click, keyboard... ?

Question

Hello;I have a script that pols a folder for files despited by some other process (getDataFiles()); when it finds a file, it processes it (processData()), then moves it to a different folder and pols for a newly depostied file. This is the loop you see below. I’m looking for a way to break the loop. I can’t, from what I’ve read, set the “isStopped” variable via a button click because of the single-thread nature of Javascript processing. Ideally, I’d like to have a UI with a start and stop button.I’ve spent a lot of time Googling, to no avail. What would you suggest?Thanks. var isStopped = false;
...
...
...

function doIt() {

while (!isStopped) {

getDataFiles();  // read the file names into var dataFiles
        
        for(i=0; i < dataFiles.length ;i++) { // if there are files,process them.
            processData(dataFiles[i].name)            
            }
        
       // wait for a bit (for new data files to be deposited)        
       $.sleep(2000)           // wait 2 seconds        
       
       }   // while !isStopped

}

Mathias Moehl · Accepted Answer

Hi Mathias; OK, I’ve created my first panel with start and stop buttons.

I’ve moved the loop to the JS from the JSX; still no luck stopping the loop, I tried a couple of things; likely for the same reason as my previous attempt.

What is your recommendation please, thanks so much for your help.

var csInterface = new CSInterface();

var isStopped = false;

var startButton = document.querySelector("#start-button");
startButton.addEventListener("click", startProc);    /* Write a helper function to pass instructions to the ExtendScript side. */

var stopButton = document.querySelector("#stop-button");
stopButton.addEventListener("click", stopProc);    /* Write a helper function to pass instructions to the ExtendScript side. */

function startProc() {
    while (!isStopped) {
         csInterface.evalScript("startProcessing()");  
     } 
}

function stopProc() {
    isStopped == true;
  }

Instead of having one function "startProcessing()" that does all the work, you need to have a function that only does a little bit of processing and then returns to give the user the chance to cancel. The evalScript has a second parameter: a function that is called when the evalScript finished. Use it to start the next bit of work.

Example:

Say you have to process each layer from 1 to 100 of a composition in whatever way. Then you could do it like this:

var firstLayer = 1;
var lastLayer = 100;

function startProc(){
	doWorkForLayer(firstLayer);
}

function doWorkForLayer(nextLayerToBeProcessed){
	csInterface.evalScript("processLayer(${nextLayerToBeProcessed})", function(){
		// this code is executed once processLayer is finished
		if(!isStopped && nextLayerToBeProcessed<= lastLayer ){
			doWorkForLayer(nextLayerToBeProcessed+1)
		}
	});  
}

Mathias Moehl · Answer

Unfortunately, Ae scripting has no concept of code running asynchronous. That means while your code is running, Ae essentially freezes and hence the user has no chance to click a button.

For anything that goes beyond a simple progress bar, I recommend to implement that as a CEP panel instead.

In CEP you can write asynchronous javascript such that the UI stays fully responsive while your file processing operations run in the background.

Sign up

To post, reply, or follow discussions, please sign in with your Adobe ID.

Sign in to Adobe Community

To post, reply, or follow discussions, please sign in with your Adobe ID.

Scanning file for viruses.

This file cannot be downloaded