Activating Browser window from within an InDesign Javascript

What about using UXP Script?
You can communicate with BridgeTalk even from versions that cannot use UXP Script.

#target "indesign"
if (parseFloat(BridgeTalk.getSpecifier("indesign", -100).split("-")[1]) < 18) {
    alert("InDesign with UXP is not installed.");
    exit();
}
if(!BridgeTalk.isRunning(BridgeTalk.getSpecifier("indesign", -100))) {
    BridgeTalk.launch(BridgeTalk.getSpecifier("indesign", -100), "background");
}
var myBridgeTalk = new BridgeTalk;
myBridgeTalk.target = BridgeTalk.getSpecifier("indesign", -100);
myBridgeTalk.body = """
    if(app.documents.count() == 0){
        app.documents.add(); // It doesn't seem to work without the document.
    }
    app.activeWindow.minimize();
    app.insertLabel("response", "");
    app.doScript(\"\"\"
        await (async () => {
            return new Promise((resolve, reject) => {
                try{
                    const xhr = new XMLHttpRequest();
                    xhr.open("GET", "https://reqres.in/api/users/2", true);
                    xhr.onload = function(){
                        app.insertLabel("response", xhr.response);
                        resolve();
                    };
                    xhr.send();
                } catch (e) {
                    resolve(e);
                }
            });
        })();
    \"\"\", ScriptLanguage.UXPSCRIPT);
    for(var i = 0; i < 100; i++){
        if(app.extractLabel("response") != ""){
            var myExtractLabelValue = app.extractLabel("response");
            break;
        }else{
            $.sleep(100);
        }
    }
    app.insertLabel("response", ""); // Remains if not initialized
    myExtractLabelValue;  // Return value
""";
myBridgeTalk.onResult = function(result) {
    alert(result.body);
}
myBridgeTalk.onError = function(error) {
    alert("Error: " + error.body);
}
myBridgeTalk.send(10000); // If not supplied or 0, the message is sent asynchronously, and the function returns immediately without waiting for a result.

I used this as a reference for XMLHttpRequest.

https://github.com/AdobeDocs/uxp-indesign/blob/main/src/pages/reference/uxp-scripting-samples/UxpModuleNetwork.idjs 

I don't know how to use fetch.
Please someone tell me.

https://developer.adobe.com/indesign/uxp/uxp/reference-js/Global%20Members/Data%20Transfers/fetch/ 

You can use the hyperlinkDestination object to launch the browser using javascript. The idea is to add a hyperlinkdestination to a document and the use its showDestination method to open the browser. See the sample code below

var h = app.documents[0].hyperlinkURLDestinations.add("www.google.com")
h.showDestination()

The above code requires a document to be opened in InDesign

-Manan

OK. Ill wait a little longer, but it looks like I cant do what I need simply in JS.

The difference in my request and the answers suggested is I already have the page open in the browser, and need to get at the variable data hidden in the page.

I will wait a little longer to see if any one else has an ideas, otherwise I will assume it cannot be done.

Thanks anyway.

Roy

*Bump*