Passing information from jsx to js.

Most of this topic went over my head. Is there a way to get information from the jsx file back to the js script in your html file? I am trying to use a folder picker in the form of:

var fPath = decodeURIComponent(Folder.selectDialog("Choose the output directory"));

I can get the path and alert from the jsx file but I cannot seem to set it to a variable to display to the user in a panel field. Is this possible? Thanks

klemenm  wrote In evalScript function the variable get's the string from jsx function but when I want to use it outside I get empty string again. Also I get the alert outside evalScript first in order. Why this happens? Does anyone know why this happens and how to fix this?

As others have pointed out, CSInterface.evalScript is an asynchronous* function.

* There is currently a bug on Adobe apps in macOS that causes evalScript to run synchronously. This doesn't help you, however, because the callback still gets scheduled to occur after the current context completes.

Here's how your code is evaluated:

1. Call to evalScript sends a request to process the code you send it.
2. Your "outside" alert is triggered. The captured variable variable is still the empty string.
3. The Panel (JS) processing (started via some callback, e.g. button click callback) completes.
4. The ExtendScript (JSX) context is started and begins to process the request you sent it.
5. The script you passed to ExtendScript (JSX) is processed, generating the return value you are interested in (coerces it to a string).
6. The ExtendScript (JSX) context sends a request to process the string to the JS using the callback you specified.
7. The panel (JS) context runs the callback that you provided to evalScript and only now will it have the chance to set the captured variable variable to the string that your JSX code produced. Your "inside" alert is triggered.

What you really want to do is run your "outside" alert after the "inside" code has had a chance to run. To do this you need to somehow get #2 to occur after #7. This is where the setTimeout function comes in handy. Try this:

(function () {  
    var cs = new CSInterface();  
    var variable = "";  
    cs.evalScript('"string"', function(result) {  
       variable = result;  
       alert("variable in evalScript =" + variable);   
    });  
    setTimeout(() => {alert("variable in outside = " + variable);}, 0);
}()); 

Note that I got rid of the special JSX-side function that simply returns "string". Rather, I just made the evalScript simply return that directly.

The important part is line 8. That schedules the anonymous, inline function to be called at a later date (the 0 at the end means "as soon as possible" - if you had heavy script in your JSX [on applications running in Windows] then you might need to delay even further with larger numbers). Honestly, though, the correct thing to do is simply trigger another function call that makes use of that captured variable from within the function itself. Both the callback passed to evalScript and the one passed to setTimeout capture a reference to the same variable instance which means that when one changes, both do. It's merely a matter of determining which callback is triggered earlier.

I hope this helps!

cs.evalScript() is an asyncronous call, meaning it will wait until it receives a reply from your jsx script before setting ‘result’ and executing the callback function your evalScript.

While asyncronous functions wait patiently before executing their callbacks, that ‘waiting’ does not halt execution of the next line of code, which in your case is the ‘outside’ alert.

So your code will execute your second ‘outside’ alert first and your first ‘in evalscript’ second.

More on asyncronous coding here Introduction to asynchronous JavaScript (Example) | hack.guides()