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Unable to import more than one level of module

I'm working on a browser app and am using the below method to import modules as needed. Unfortunately any modules imported at the 'second level' or deeper treat the asterisk '*' as an unexpected token. It's been a few years since my last JavaScript work and am unsure what I'm doing wrong as much has changed and is new to me.
Below is a minimum example that encounters the issue. The structure of each module is to emulate C# classes with public, private, and static objects and almost entirely remove the need to type 'this.' over and over and over again as is the .js way of doing things.
Content.js
//Directly attached to the page using <script type="module" src="Content.js"></script>
import * as XRVideo from "../Viewer/Scripts/XRVideo.js"; //This works perfectly
var urlA = "Testing/VideoA.mp4";
var urlB = "Testing/VideoB.mp4";
var arrXRVideos = [];
window.addEventListener("load", (e) =>{
arrXRVideos.Push(XRVideo.New(urlA));
arrXRVideos.Push(XRVideo.New(urlB));
});
XRVideo.js
import * as XRScene from "./Core/XRScene.js"; //This throws an Unexpected Token '*' Error
import * as XRSkybox from "./Core/XRSkybox.js";
/* Static */
export const XRStatus = {
Stopped : 0,
};
/* Instanced */
export function New(videoURL){
var _isInitialized = false;
var _url = "";
//#region Pseudo Constructor
{
_url = videoUrl;
_isInitialized = true;
}
//#endregion
/* Getters & Setters */
function GetURL(){
return _url;
}
/* Exposed As Public */
//Properties can't be directly exposed otherwise they become static...
return{
GetURL : GetURL
}
}

It turned out the issue was due to a broken line comment throwing off the system. Always look at the previous line for 'Unexpected' errors...
I didn't notice this due to how VS Code's Default theme, visually styles code comments and hyperlinks the same. Specifically both lines look like the same green text despite one being a comment and the other not.
//This is a comment, VS Code shows it as a dirty green.
//I am a code comment
//This is a URL that accidentally didn't get the '//' to turn it into a comment,
//VS Code shows it as a dirty green making it look like a comment.
https://github.com/blah-blah-blah
import * as Bah from "./Foo.js"; //Unexpected token '*'

How to avoid default errors from a library

I have created a code that it actually works, but I call a library that has an error, and I would like to know if it is possible to avoid that specific line of code. I will try to explain the case as well as possible:
Error
Uncaught TypeError: fs.openSync is not a function
Previous code
function synthesizeToAudioFile(authorizationToken, message) {
// replace with your own subscription key,
// service region (e.g., "westus"), and
// the name of the file you save the synthesized audio.
var serviceRegion = "westus"; // e.g., "westus"
var filename = "./audiocue.wav";
//Use token.Otherwise use the provided subscription key
var audioConfig, speechConfig;
audioConfig = SpeechSDK.AudioConfig.fromAudioFileOutput(filename);
speechConfig = SpeechSDK.SpeechConfig.fromAuthorizationToken(authorizationToken, serviceRegion);
// create the speech synthesizer.
var synthesizer = new SpeechSDK.SpeechSynthesizer(speechConfig, audioConfig);
// start the synthesizer and wait for a result.
synthesizer.speakTextAsync(message,
function (result) {
if (result.reason === SpeechSDK.ResultReason.SynthesizingAudioCompleted) {
console.log("synthesis finished.");
} else {
console.error("Speech synthesis canceled, " + result.errorDetails +
"\nDid you update the subscription info?");
}
synthesizer.close();
synthesizer = undefined;
},
function (err) {
console.trace("err - " + err);
synthesizer.close();
synthesizer = undefined;
});
console.log("Now synthesizing to: " + filename);
}
I created a method, which later I have replicated in my current code. The difference was that I was using Browserify in order to import a library from a script of a HTML file:
<script type="text/javascript" src="js/dist/sub_mqtt.js"></script>
This file had my method, and the whole library, which made it crazy unreadable, and therefore I started using ScriptJS to import it. The problem is that, using browserify I was able to remove the line of code that it was failing using fs.openSync(and I do not even need), but by importing it with ScriptJS I do not have access to the source code.
I assume that what is missing is that I am not importing the library fs, which is being used by the library that I am importing with ScriptJS before importing that one, but how could I do it? I have tried:
<script src="../text-to-speech/node_modules/fs.realpath/index.js"></script>
, or
<script type="text/javascript" src="../text-to-speech/node_modules/fs.realpath/index.js"></script>
and also wrapping the content of synthesizeToAudioFile() with
require(["node_modules/fs.realpath/index.js"], function (fs) { });
but I get the following error:
Uncaught ReferenceError: module is not defined
at index.js:1

After researching about this question I found out the next statement:
The fs package on npm was empty and didn't do anything, however many
packages mistakenly depended on it. npm, Inc. has taken ownership of
it.
It's also a built-in Node module. If you've depended on fs, you can
safely remove it from your package dependencies.
therefore what I have done is to access to the file that I was requiring with ScriptJS
require(["../text-to-speech/microsoft.cognitiveservices.speech.sdk.bundle.js"]
and directly remove that line on it. Note that, at least in my case, clearing the cache of the browser was needed.

How to run V8 evaluation multiple times?

Maybe it is stupid question (I am newbie to C++, just wanted to use it as library for android), but I am not able to run evaluation of some JS multiple times.
I have started with "hello world" tutorial. But then I have wanted simple thing, re-run main (just wrap content of tutorial code into function and run it twice in newly empty main.
This is what I got:
#
# Fatal error in ../src/isolate.cc, line 1868
# Check failed: thread_data_table_.
#
==== C stack trace ===============================
1: 0xa890b9
2: 0x6a22fc
3: 0x42694f
4: 0x405f66
5: 0x405ec7
6: __libc_start_main
7: 0x405dc9
Illegal instruction (core dumped)
This cames after creating new isolate
Isolate* isolate = Isolate::New(create_params);
Well, what I should do? Am I using wrong construct or so? Should I close/delete/clear something more?
In bigger view I just want to do evaluate function, that can be triggered multiple times, and beside that also run multiple js snipets in same context (how to split this function?).
Any idea?
UPDATE:
Ok, lets say that the main can be split into three logical parts:
init
int main(int argc, char* argv[]) {
// Initialize V8.
V8::InitializeICU();
V8::InitializeExternalStartupData(argv[0]);
Platform* platform = platform::CreateDefaultPlatform();
V8::InitializePlatform(platform);
V8::Initialize();
// Create a new Isolate and make it the current one.
ArrayBufferAllocator allocator;
Isolate::CreateParams create_params;
create_params.array_buffer_allocator = &allocator;
evaluation
Isolate* isolate = Isolate::New(create_params);
{
Isolate::Scope isolate_scope(isolate);
// Create a stack-allocated handle scope.
HandleScope handle_scope(isolate);
// Create a new context.
Local<Context> context = Context::New(isolate);
// Enter the context for compiling and running the hello world script.
Context::Scope context_scope(context);
// Create a string containing the JavaScript source code.
Local<String> source =
String::NewFromUtf8(isolate, "'Hello' + ', World!'",
NewStringType::kNormal).ToLocalChecked();
// Compile the source code.
Local<Script> script = Script::Compile(context, source).ToLocalChecked();
// Run the script to get the result.
Local<Value> result = script->Run(context).ToLocalChecked();
// Convert the result to an UTF8 string and print it.
String::Utf8Value utf8(result);
printf("%s\n", *utf8);
}
isolate->Dispose();
and clean
// Dispose and tear down V8.
V8::Dispose();
V8::ShutdownPlatform();
delete platform;
return 0;
Now as I said before if I run main consists of init->evaluation->clean twice, that mean init->evaluation->clean->init->evaluation->clean, then the error occurs. I have figured out, that if I extract evaluation part into separate function I can run it multiple times e.g. as init->(evaluation){2}->clean
Is that how should it work? Next step is to divide this main into tree separate function that mean I have to have static member with platform? Could it cause leak somehow?
NOTE: that I want to run it from android, that mean e.g. click in UI, propagate js source to C via JNI and then call c++ V8, which is already initialized or not. hm?
Prefered way is to have "blackbox", but if I have to hold platform, so be it. It maybe could be also faster without re-initialization of V8, right?
UPDATE 2:
Well, still have problems with splitting evaluation part to achieve multiple runs in same isolate/context.
I have splitted it after creating context with stored isolate and context, but with no luck. When in second part try to create source string it fails, probably because of using stored isolate (something with isolate scope I guess).
:(

My assumption as I introduced in UPDATE1 was correct. That part works well.
According to UPDATE2 I have splitted evaluation part into two.
First for initialize isolate and context:
mIsolate = Isolate::New(mCreate_params);
Isolate::Scope isolate_scope(mIsolate);
{
// Create a stack-allocated handle scope.
HandleScope handle_scope(mIsolate);
v8::Handle<v8::ObjectTemplate> global = v8::ObjectTemplate::New(mIsolate);
// Bind the global 'print' function to the C++ Print callback.
global->Set(v8::String::NewFromUtf8(mIsolate, "print"), v8::FunctionTemplate::New(mIsolate, Print));
// Create a new context.
mContext = Context::New(mIsolate, NULL, global);
Persistent<Context, CopyablePersistentTraits<Context>> persistent(mIsolate, mContext);
mContext_persistent = persistent;
}
and second that will run js in same context:
Isolate::Scope isolate_scope(mIsolate);
{
HandleScope handle_scope(mIsolate);
mContext = Local<Context>::New(mIsolate, mContext_persistent);
// Enter the context for compiling and running the hello world script.
Context::Scope context_scope(mContext);
{
// Create a string containing the JavaScript source code.
Local<String> source =
String::NewFromUtf8(mIsolate, js_source, NewStringType::kNormal).ToLocalChecked();
// Compile the source code.
Local<Script> script = Script::Compile(mContext, source).ToLocalChecked();
TryCatch trycatch(mIsolate);
// Run the script to get the result.
v8::Local<v8::Value> result;
if(!script->Run(mContext).ToLocal(&result)){
v8::String::Utf8Value exception_str(trycatch.Exception());
dprint(*exception_str);
}else{
if(!result->IsUndefined()){
String::Utf8Value utf8(result);
dprint(*utf8);
}
}
}
}
Well the code works very well on linux, but I still have some issues when I try to run first part for the second time (create new context) on android:
A/art: art/runtime/thread.cc:986] pthread_getschedparam failed for DumpState: No such process
A/art: art/runtime/base/mutex.cc:485] Unexpected state_ 0 in unlock for logging lock
But that's another question I guess. Peace.

Did you initialize v8 more than once?
v8::V8::Initialize() this method should be called once per process.
deep into project source file "v8/src/v8.cc", you will find the prove
bool V8::Initialize() {
InitializeOncePerProcess();
return true;
}

Windows 8 IndexedDB createObjectStore

Trying to build a Metro app using Javascript and having issues with IndexedDb. I cannot create an object store. My code is shown below. I'm doing this on success of the open() function.
dbReq.onsuccess = function (evt) {
var txn = evt.target.transaction;
var db = evt.target.result;
if (!db.objectStoreNames.contains("test")) {
var store = db.createObjectStore("test");
}
}
Every time, it throws an exception on the 'createObjectStore' call that says
0x800a139e - JavaScript runtime error: [object IDBDatabaseException]
Over here they talk about it and it's a nice example to look at too, but still, did not help me.
Notice that control hits the one line of code inside 'if' statement. So 'db' is not null and is valid. But I saw that the transaction is null - not sure if that is an issue or even if you are supposed to get a valid transaction back at this point.

Not sure why it was not working. Switched to using roaming settings and it is very easy to use.
roamingSettings.values[SETTING_NAME] = SETTING_VALUE;
To read, of course,
var temp = roamingSettings.values[SETTING_NAME];

Load "Vanilla" Javascript Libraries into Node.js

There are some third party Javascript libraries that have some functionality I would like to use in a Node.js server. (Specifically I want to use a QuadTree javascript library that I found.) But these libraries are just straightforward .js files and not "Node.js libraries".
As such, these libraries don't follow the exports.var_name syntax that Node.js expects for its modules. As far as I understand that means when you do module = require('module_name'); or module = require('./path/to/file.js'); you'll end up with a module with no publicly accessible functions, etc.
My question then is "How do I load an arbitrary javascript file into Node.js such that I can utilize its functionality without having to rewrite it so that it does do exports?"
I'm very new to Node.js so please let me know if there is some glaring hole in my understanding of how it works.
EDIT: Researching into things more and I now see that the module loading pattern that Node.js uses is actually part of a recently developed standard for loading Javascript libraries called CommonJS. It says this right on the module doc page for Node.js, but I missed that until now.
It may end up being that the answer to my question is "wait until your library's authors get around to writing a CommonJS interface or do it your damn self."

Here's what I think is the 'rightest' answer for this situation.
Say you have a script file called quadtree.js.
You should build a custom node_module that has this sort of directory structure...
./node_modules/quadtree/quadtree-lib/
./node_modules/quadtree/quadtree-lib/quadtree.js
./node_modules/quadtree/quadtree-lib/README
./node_modules/quadtree/quadtree-lib/some-other-crap.js
./node_modules/quadtree/index.js
Everything in your ./node_modules/quadtree/quadtree-lib/ directory are files from your 3rd party library.
Then your ./node_modules/quadtree/index.js file will just load that library from the filesystem and do the work of exporting things properly.
var fs = require('fs');
// Read and eval library
filedata = fs.readFileSync('./node_modules/quadtree/quadtree-lib/quadtree.js','utf8');
eval(filedata);
/* The quadtree.js file defines a class 'QuadTree' which is all we want to export */
exports.QuadTree = QuadTree
Now you can use your quadtree module like any other node module...
var qt = require('quadtree');
qt.QuadTree();
I like this method because there's no need to go changing any of the source code of your 3rd party library--so it's easier to maintain. All you need to do on upgrade is look at their source code and ensure that you are still exporting the proper objects.

There is a much better method than using eval: the vm module.
For example, here is my execfile module, which evaluates the script at path in either context or the global context:
var vm = require("vm");
var fs = require("fs");
module.exports = function(path, context) {
context = context || {};
var data = fs.readFileSync(path);
vm.runInNewContext(data, context, path);
return context;
}
And it can be used like this:
> var execfile = require("execfile");
> // `someGlobal` will be a global variable while the script runs
> var context = execfile("example.js", { someGlobal: 42 });
> // And `getSomeGlobal` defined in the script is available on `context`:
> context.getSomeGlobal()
42
> context.someGlobal = 16
> context.getSomeGlobal()
16
Where example.js contains:
function getSomeGlobal() {
return someGlobal;
}
The big advantage of this method is that you've got complete control over the global variables in the executed script: you can pass in custom globals (via context), and all the globals created by the script will be added to context. Debugging is also easier because syntax errors and the like will be reported with the correct file name.

The simplest way is: eval(require('fs').readFileSync('./path/to/file.js', 'utf8'));
This works great for testing in the interactive shell.

AFAIK, that is indeed how modules must be loaded.
However, instead of tacking all exported functions onto the exports object, you can also tack them onto this (what would otherwise be the global object).
So, if you want to keep the other libraries compatible, you can do this:
this.quadTree = function () {
// the function's code
};
or, when the external library already has its own namespace, e.g. jQuery (not that you can use that in a server-side environment):
this.jQuery = jQuery;
In a non-Node environment, this would resolve to the global object, thus making it a global variable... which it already was. So it shouldn't break anything.
Edit:
James Herdman has a nice writeup about node.js for beginners, which also mentions this.

I'm not sure if I'll actually end up using this because it's a rather hacky solution, but one way around this is to build a little mini-module importer like this...
In the file ./node_modules/vanilla.js:
var fs = require('fs');
exports.require = function(path,names_to_export) {
filedata = fs.readFileSync(path,'utf8');
eval(filedata);
exported_obj = {};
for (i in names_to_export) {
to_eval = 'exported_obj[names_to_export[i]] = '
+ names_to_export[i] + ';'
eval(to_eval);
}
return exported_obj;
}
Then when you want to use your library's functionality you'll need to manually choose which names to export.
So for a library like the file ./lib/mylibrary.js...
function Foo() { //Do something... }
biz = "Blah blah";
var bar = {'baz':'filler'};
When you want to use its functionality in your Node.js code...
var vanilla = require('vanilla');
var mylibrary = vanilla.require('./lib/mylibrary.js',['biz','Foo'])
mylibrary.Foo // <-- this is Foo()
mylibrary.biz // <-- this is "Blah blah"
mylibrary.bar // <-- this is undefined (because we didn't export it)
Don't know how well this would all work in practice though.

I was able to make it work by updating their script, very easily, simply adding module.exports = where appropriate...
For example, I took their file and I copied to './libs/apprise.js'. Then where it starts with
function apprise(string, args, callback){
I assigned the function to module.exports = thus:
module.exports = function(string, args, callback){
Thus I'm able to import the library into my code like this:
window.apprise = require('./libs/apprise.js');
And I was good to go. YMMV, this was with webpack.

A simple include(filename) function with better error messaging (stack, filename etc.) for eval, in case of errors:
var fs = require('fs');
// circumvent nodejs/v8 "bug":
// https://github.com/PythonJS/PythonJS/issues/111
// http://perfectionkills.com/global-eval-what-are-the-options/
// e.g. a "function test() {}" will be undefined, but "test = function() {}" will exist
var globalEval = (function() {
var isIndirectEvalGlobal = (function(original, Object) {
try {
// Does `Object` resolve to a local variable, or to a global, built-in `Object`,
// reference to which we passed as a first argument?
return (1, eval)('Object') === original;
} catch (err) {
// if indirect eval errors out (as allowed per ES3), then just bail out with `false`
return false;
}
})(Object, 123);
if (isIndirectEvalGlobal) {
// if indirect eval executes code globally, use it
return function(expression) {
return (1, eval)(expression);
};
} else if (typeof window.execScript !== 'undefined') {
// if `window.execScript exists`, use it
return function(expression) {
return window.execScript(expression);
};
}
// otherwise, globalEval is `undefined` since nothing is returned
})();
function include(filename) {
file_contents = fs.readFileSync(filename, "utf8");
try {
//console.log(file_contents);
globalEval(file_contents);
} catch (e) {
e.fileName = filename;
keys = ["columnNumber", "fileName", "lineNumber", "message", "name", "stack"]
for (key in keys) {
k = keys[key];
console.log(k, " = ", e[k])
}
fo = e;
//throw new Error("include failed");
}
}
But it even gets dirtier with nodejs: you need to specify this:
export NODE_MODULE_CONTEXTS=1
nodejs tmp.js
Otherwise you cannot use global variables in files included with include(...).