Get JSON data from URL into field form via button

[Finn2756598933bq]

Hello,
I have seen similar topics but none seem to fit to my case. So I would like to fetch a JSON array from a web application in our local network once a button gets triggered by a user. Then the JS should write a value from that JSON array into a field on the PDF. Unfortunately it does not work. I have tested the code inside VSCode and it works fine there... What am I missing? Any help appreciated.

app.beginPriv();

fetch("http://domainXYZ/ajax/server_processing.php")
.then(response => response.json())
.then(data => {

const theData = data[0];

var dataConv = eval("(" + theData[0] + ")");

var FName = dataConv.Firstname;
});

this.getField('1').value = FName;

app.endPriv();

[Bernd Alheit]

Check the Javascript console for errors.

[Test Screen Name]

I'm not at all convinced you can use the Promise API in Acrobat. Have you just lifted this code from browser JavaScript? Adobe Acrobat Javascript Promises - Stack Overflow

[Thom Parker · Accepted solution]

There is no "fetch" function in the Acrobat JavaScript model.  

However, there is an "HTTP.Net" object that can be used to perform HTTP operations.

https://opensource.adobe.com/dc-acrobat-sdk-docs/library/jsapiref/JS_API_AcroJS.html#net-http

It cannot be used from a document script. The only internet access from within an untrusted document context is the form submit.  

https://opensource.adobe.com/dc-acrobat-sdk-docs/library/jsapiref/doc.html#submitform

It's always helpful to look at the actual documentation.