Develop Reference

How do we find the definition of a variable using VSCode's Extensions API?

Is there a way to find the definition of a variable using VSCode's Extensions API for a TSX/TS project if the variable is defined in another file?
For example:
// file_1.tsx
const randomConstantVariable = "Hello World"
// file_2.tsx
import { randomConstantVariable } from "./someFile.ts"
console.log(randomConstantVariable)
I would like to access the definition of the randomConstantVariable in my Hover Provider when I'm working on file_2.tsx, but I'm not sure if there's an built-in way to do it using VSCode's Extensions API.
I tried using vscode.commands.executeCommand("vscode.workspaceSymbolProvider", "randomConstantVariable") but it can't seem to find file_1.tsx.
It seems like it's possible, since when I hover over a variable, VSCode is able to pick up the definition to display on the pop-up. I just wonder if this feature is somewhere in their API that I'm not seeing or if it's just built into VSCode but not exposed to the API.

Kotlin, how can I read a dynamic website as text?

As titled, I'm trying to read the content of sites like this one, which appears to be javascript based.
I tried using plain jdk lib, then jsoup and then htmlunit, but I couldn't get anything useful out of it (I see just the source code or just the title or null):
val url = URL("https://registry.terraform.io/providers/hashicorp/tls/latest/docs/data-sources/certificate")
val connection = url.openConnection()
val scanner = Scanner(connection.getInputStream())
scanner.useDelimiter("\\Z")
val content = scanner.next()
scanner.close()
println(content)
val doc = Jsoup.connect("https://registry.terraform.io/providers/hashicorp/tls/latest/docs/data-sources/certificate").get()
println(doc.text())
WebClient().use { webClient ->
val page = webClient.getPage<HtmlPage>("https://registry.terraform.io/providers/hashicorp/tls/latest/docs/data-sources/certificate")
val pageAsText = page.asNormalizedText()
println(pageAsText)
}
WebClient(BrowserVersion.FIREFOX).use { webClient ->
val page = webClient.getPage<HtmlPage>("https://registry.terraform.io/providers/hashicorp/tls/latest/docs/data-sources/certificate")
println(page.textContent)
}
It should be something easy peasy, but I cant see what's wrong

In order for this to be possible, you need something to execute the JS that modifies the DOM.
It might be a bit overkill depending on the use case, and probably won't be possible if you're on Android, but one way to do this is to launch a headless browser separately and interact with it from your code. For instance, using Chrome Headless and the Chrome DevTools Protocol. If you're interested, I have written a Kotlin library called chrome-devtools-kotlin to interact with a Chrome browser in a type-safe way.
There might be simpler options, though. For instance maybe you can run an embedded browser instead with JBrowserDriver and still use JSoup to parse the HTML, as mentioned in this other answer.

Regarding HtmlUnit:
the page has initially no content, all you see is rendered from javascript magic on the client side using one of this spa frameworks.
It looks like there is some feature check in the beginning that figures out the js support in HtmlUnit does not have all the required features and based on this you only get a hint like "Please enable Javascript to use this application".
You can use
page.asXml()
to have a look at the content trough HtmlUnit's eyes.
You can open an HtmlUnit issue on github but i fear adding support for this will be a longer story.

Debug dynamically loaded JavaScript code with IntelliJ and the Nashorn engine

I am dynamically loading and running JavaScript code that is stored on disk in a YAML file. I would like to know if it is possible (using intelliJ) to debug the JS code even though I am not loading it from a standalone JS file. To simplify the problem description, consider the following Java code:
NashornScriptEngineFactory nashornFactory = new NashornScriptEngineFactory();
ScriptEngine engine = nashornFactory.getScriptEngine();
engine.eval("var a = 1 + 1;\nprint(a);");
How do I set a breakpoint on line two (the "print" function call) and how do I examine the value of variable "a"? If this is not possible, what would be the best workaround?

Based on this blog post https://blogs.oracle.com/sundararajan/remote-debugging-of-nashorn-scripts-with-netbeans-ide-using-debugger-statements, you can just attach a remote java debugger to process.
You can do this in IntelliJ IDEA by creating a new remote run configuration.
After attaching, use the JavaScript command:
debugger;
This will force the debugger to break if it is attached. You can then inspect the values of variables within the variable window.
If you can't manage to attach IntelliJ, open the browsers inspector/debugger and this same line of javascript will cause the browser's debugger to break on that line.

Using third-party JS libraries in Mozilla Add-On SDK

I'm starting a new project (Firefox add-on) and I'd like to try using behavior-driven development. I particularly like the Jasmine BDD library. However, I can't find a good way how to use a framework such as Jasmine in the Add-On SDK.
One problem is that Jasmine needs setTimeout (and similar) functions to be specified on the global object, whereas Add-On SDK exports those using "timers" module. But let's say I tweak Jasmine to get those object from "timers" (or add the the methods exported by timers to the global object).
The bigger problem is that I don't know how to actually run the tests. There is a test directory generated by the SDK, however, there's no window or document object there to allow me to see the output (and I'd really like to see the fancy HTML output). I guess I could create a content script that would modify the page, but then I can't access (test) the background script.
Have you ever faced this before? Is there any recommended way how to deal with that?
Thanks!
Tomas

You can use the Add-on SDK windows API to open a new window to run your tests in. You should be able to load the Jasmine script(s) with the subscript loader and set window and document to whatever you want in the scope of that subscript:
var windows = require("windows").browserWindows;
windows.open({
url: "about:blank",
onOpen: function(window) {
var script;
var scriptLoader = Cc["#mozilla.org/moz/jssubscript-loader;1"].
getService(Ci.mozIJSSubScriptLoader);
scriptLoader.loadSubScript(subscriptSpec, script);
script["window"] = window;
script["document"] = window.document;
// ... run your tests here by calling script.someFunc() ...
}
});
Update: Further research shows that the browserWindows are actually special wrappers that don't give you access to the content window. You might try getting a window/document from a hidden frame. That's the only way I can see to get access to an HTML document from privileged code.

Tutorial for using JavaScript on a Desktop

I need to do some scripts in java script.
I am working on it but couldn't find a few solutions to a few problems.
First of all I need a GOOD tutorial, but not for an internet page but for a DESKTOP script.
Things couldn't find out like :
1) I wanted a simple message box in order to debug my program, I used:
var name = prompt("What is your name","Type Name Here");
When running it I get error of "Object expected"
2) Couldn't find how to open a file

Based on your comments, I guess that you are attempting to run a JavaScript file directly on Windows. Double-clicking on a .js file in windows will (probably) run it in Windows Script Host.
The prompt() function will not work this way, since WSH provides a completely different API than browser-embedded engines.
The following code should accomplish your intentions. However if you want anything more than a simple popup, HTAs are the only way to do complex GUIs with JScript on the desktop.
var fso, ws, ts;
fso = new ActiveXObject('Scripting.FileSystemObject');
ws = WScript.CreateObject('WScript.Shell');
var ForWriting= 2;
ts = fso.OpenTextFile('foo.txt', ForWriting, true);
ts.WriteLine(new Date().getTime());
ts.Close();
ws.Popup('Wrote to file!');
var ForReading= 1;
ts = fso.OpenTextFile('foo.txt', ForReading, false);
var fileContents = ts.ReadLine();
ts.Close();
ws.Popup('The file contained: ' + fileContents);
WScript.Quit();

I have to ask: why is JavaScript the right tool for the job? Why not use a scripting language intended to be used this way, such as Python, Ruby, Lua, ... etc?
If you are using Microsoft's JScript (and it sounds like you are), look to the MSDN web site for help. The page here looks fairly good. Google can also help with that.
Assuming you don't mind using Java, you could also use the Mozilla Rhino shell. But it doesn't look like there is a standard way of reading from the console in JavaScript. (presumably since this is not something typically required in a JavaScript application...) The built in JavaScript functions in the shell seem fairly basic, but you can read a file.
There area also examples of using Rhino, which may be helpful. You can interface with the Java API to do whatever else you need to do.
Edit: I wrote this answer a long time ago; today I would use node.js. See their learning page.

The latest prerelease of Opera acts as a runtime for JS applications.
They have tutorials describing how to use it.
I used: var name = prompt("What is your name","Type Name Here");
When running it I get error of "Object expected"
Presumably your runtime doesn't implement prompt that in a way that is compatible with those arguments.
2) Couldn't find how to open a file
This depends on the runtime you use. JS itself doesn't have anything built in to read files (or display a prompt). You need an environment that provides those objects.