So this may be naive, but can I run node only style apps in the browser? I've see tuts for frontend stuff. I've seen tuts for backend stuff. I want to run https://github.com/lapwinglabs/x-ray in a browser and do something quick and dirty like (this code may not be perfect)
$(document).ready(function() {
var phantom = require('x-ray-phantom');
var Xray = require('x-ray');
var x = Xray()
.driver(phantom());
x('http://google.com', 'body')(function(err, str) {
$( "body" ).replaceWith( "str" );
});
});
To do a whole site pass though without an iframe. The purpose is so I can re-write CSS on internal company assets in sort of a global fashion. I'll be able to just pass a url and the page will be displayed. If I have custom css for it, then that will be active. I still gotta work out auth, but im not worried about it at this exact moment.
I've used x-ray with express in the past and it worked like a charm. In this context though I've taken a liking to Laravel and would like to stand up my apps in that.
The latest Laravel has "mix", a web pack front end. It works great for frontend assets. If I try to webpack x-ray though, I run into a flurry of issues like:
Module not found: Error: Can't resolve yadayadayada
So you can set an export like this:
module.exports.node = {
fs: 'empty',
net: 'empty',
tls: 'empty'
};
While that fixes module errors, I feel like I need those things. and in the browser I get:
Uncaught Error: Cannot find module "child_process"
I have a feeling things like this are not supposed to work, but I'm hoping I'm mistaken.
The simple answer is: you can't use Node built-in modules like fs or net, and therefore modules that use them, in the browser.
You can empty them out as you did with the node option, but the modules that depend on them use them for a reason and you would break them, unless you know exactly that the part, that uses the built-in modules, will not end up in your application, or at least you're not using it.
In your case, first it complained about fs, which clearly doesn't make sense in the browser, because you don't have access to the file system. And then it complains about child_process, so somewhere in the module it spawns processes, but you can't do that in the browser either, and emptying that out will very likely break the module's functionality, so you'd need to look for another module, that can be used in the browser.
Related
I'm writing some tests for my React-Native application (using JS) in a NodeJS environment. In one scenario, I need to attach to an already-running Windows application. In order to attach to this Application, I need to know the NativeWindowHandle value.
For example, if you open Inspect.exe on a window, you'll find the "NativeWindowHandle" hex value.
Is there anyway I can find this value programmatically?
What I've Tried:
I'm able to find the PID of the app using:
const exec = require('child_process').exec;
exec('tasklist', function (err, stdout) {
....
}}
However, I haven't been able to turn that into the window handle. Does anyone have any ideas here? Is this possible?
This can be reliably accomplished by writing a native (C++) node addon which calls the appropriate Windows API functions and passes the results back to JS land.
eg you might want to call FindWindowEx and Windows will find and return the HWND (native window handle) of the matching open window. Or use one of the enumeration functions if you need to do the search yourself.
I did a quick search of npm and it looks like there might be a few packages that have done this work already, but you'll need to evaluate them.
If none of the npm packages will work, you'll need to write it yourself. This isn't too hard if you have a little C++ knowledge, but alternatively you might be able to get away with using node-ffi, which lets you write everything in JS and marshals the native calls for you.
(Using ffi will be a little slower than writing the native module yourself, but for your purposes that doesn't really matter. Either native or ffi will be much faster than spawning child processes.)
I am working on a ScriptManager class for a project that was created many years ago. The original code read scripts from a database, and these scripts are different depending on the customer and installation (the application is a desktop app that uses Chrome Embedded Framework to display web pages). The code would read custom JavaScript code and eval() it, which of course is highly undesirable.
I am replacing this code with a ScriptManager class that can support dynamically inserted code, and the ScriptManager is capable of loading code as a module using JavaScript's dynamic import() command, or loading code as pure script by creating a script tag dynamically in the document.
My problem is that there are many different possible custom code blocks in the database, and not all are modules; some will be pure script until those can be converted to modules at a later time. My code can handle this as described above, but I need a way to detect if the script code from the database is a module, so I can either use the import() command or insert a script tag if it is not.
I am solving this temporarily by making sure any module script code has "export const isModule = true", and checking this after calling import(). This works, but any code that is pure script still results in a module variable, but with no exports in it. If possible I don't want the other developers to have to remember to add isModule = true to any modules they develop in the future.
Is there a way to check that code is a module without having to do complex analysis of the code to check if there are exports in it? Since import() still returns an object and throws no errors if there are no exports, I don't know how to detect this.
UPDATE: Here are some examples of how this is intended to work:
// Not real code, pretend that function gets the string of the script.
let code = getSomeCodeFromTheDatabase();
// Save the code for later loading.
let filename = 'some-filename.js';
saveCodeToFile(code, filename);
// Attempt to dynamically import the script as a module.
let module = await import(filename);
// If it is NOT a module, load it instead as a script tag.
// This is where I need to be able to detect if the code is
// a module or pure script.
if (!module.isModule) {
let scriptTag = document.createElement('script');
scriptTag.src = filename;
document.head.appendChild(script);
}
So if you look here How can I tell if a particular module is a CommonJS module or an ES6 module? you will see I answered a similar question.
So the thing is Sarah, modules are defined by the way that they resolve. Module-types resolving differently is what, not only makes them incompatible with one another, but it is also why we name them differently. Originally Transpillers like Babel & TypeScript were invented because of differences in ECMA-262 Specifications, and the desire to support people who didn't have the updated specifications, as well as supporting the newer features for those who did.
Today transpilers are still being used, conceptually, much the same way. They still help us maintain a single code base while supporting older specifications, and features in newer specifications, at the same time, but the also have the added benefit of being able to generate multiple different builds from a single code base. They use this to support different module types. In node.js, the primary module-type is CJS, but the future lies in ESM modules, so package maintainers have opted to dual build the projects. The use the TypeScript Compiler (aka Transpiler) to emit a CJS build, and an ESM build.
Now this is where things get complicated, because you cannot tell just by looking at a module if it CJS or ESM in this situation, **you absolutely have to inspect its code, and check if it has more than one tsconfig.json file (because it would need at-least 2 to maintain a bi-modular build (which are becoming increasingly common with the turn of each day)
My Suggestion to You:
Use well documented packages. Good packages should be documented well, and those packages should state in their README.md document, what type of package/module they are, and if the package supports more than one module type. If in doubt you can either come and ask here, or better yet, you can ask the maintainer by creating an issue, asking them to add that information to their README.md document.
You can check that there are no export after import. In chrome import() added empty default for non module.
function isNotModule(module) {
return (!Object.keys(module).length) || (!!module.default && typeof module.default === 'object' && !Object.keys(module.default).length)
}
import('./test.js')
.then((module) => {
console.log('./test.js',isNotModule(module))
})
May be it's better to check source code via regex to check if it contains export
something like this
const reg = new RegExp('([^\w]|^)export((\s+)\w|(\s*{))')
reg.test(source)
Sorry I don't know if this is a stupid question or not but I cannot find the answer.
I have a pure function in javascript which check if the argument is a correct URL
isValidUrl(url) {
const protocol = new URL(url).protocol;
...
}
The code runs fine in browser. But I would like to write a test using mocha for it. And mocha complains "ReferenceError: URL is not defined". So does that mean server side JS does not have URL class? Do I need to use something like headless browser to test it?
Thanks a lot.
Node and friends, where your tests are likely running, implement the ECMAScript (JS) spec. The URL class is from this WhatWG spec. The JS spec does not have any reference to a URL class, which explains your immediate problem.
Node also implements its own CommonJS-based modules, one of which is a URL module. It doesn't appear to have the same interface, however.
Using Mocha with Karma to run tests in a headless browser, like PhantomJS, is probably a better solution. You'll get an accurate, if slightly out of date, version of chromium to test within. You can also set Karma up to use other browsers, if they are available on the test machine.
I use TypeScript to code my javascript file with Object Oriented Programing.
I want to use the node module https://npmjs.org/package/typescript-require to require my .ts files from other files.
I want to share my files in both server and client side. (Browser) And that's very important. Note that the folder /shared/ doesn't mean shared between client and server but between Game server and Web server. I use pomelo.js as framework, that's why.
For the moment I'm not using (successfully) the typescript-require library.
I do like that:
shared/lib/message.js
var Message = require('./../classes/Message');
module.exports = {
getNewInstance: function(message, data, status){
console.log(requireTs);// Global typescript-require instance
console.log(Message);
return new Message(message, data, status);
}
};
This file need the Message.js to create new instances.
shared/classes/Message.ts
class Message{
// Big stuff
}
try{
module.exports = Message;
}catch(e){}
At the end of the fil I add this try/catch to add the class to the module.exports if it exists. (It works, but it's not really a good way to do it, I would like to do better)
If I load the file from the browser, the module.export won't exists.
So, what I did above is working. Now if I try to use the typescript-require module, I'll change some things:
shared/lib/message.js
var Message = requireTs('./../classes/Message.ts');
I use requireTs instead of require, it's a global var. I precise I'm using .ts file.
shared/classes/Message.ts
export class Message{
// Big stuff
}
// remove the compatibility script at the end
Now, if I try like this and if I take a look to the console server, I get requireTs is object and Message is undefined in shared/lib/message.js.
I get the same if I don't use the export keyword in Message.ts. Even if I use my little script at the end I get always an error.
But there is more, I have another class name ValidatorMessage.ts which extends Message.ts, it's not working if I use the export keyword...
Did I did something wrong? I tried several other things but nothing is working, looks like the typescript-require is not able to require .ts files.
Thank you for your help.
Looking at the typescript-require library, I see it hasn't been updated for 9 months. As it includes the lib.d.ts typing central to TypeScript (and the node.d.ts typing), and as these have progressed greatly in the past 9 months (along with needed changes due to language updates), it's probably not compatible with the latest TypeScript releases (just my assumption, I may be wrong).
Sharing modules between Node and the browser is not easy with TypeScript, as they both use very different module systems (CommonJS in Node, and typically something like RequireJS in the browser). TypeScript emits code for one or the other, depending on the --module switch given. (Note: There is a Universal Module Definition (UMD) pattern some folks use, but TypeScript doesn't support this directly).
What goals exactly are you trying to achieve, and I may be able to offer some guidance.
I am doing the same and keep having issues whichever way I try to do things... The main problems for me are:
I write my typescript as namespaces and components, so there is no export module with multiple file compilation you have to do a hack to add some _exporter.ts at the end to add the export for your library-output.js to be importable as a module, this would require something like:
module.exports.MyRootNamespace = MyRootNamespace
If you do the above it works, however then you get the issue of when you need to reference classes from other modules (such as MyRootNamespace1.SomeClass being referenced by MyRootNamespace2.SomeOtherClass) you can reference it but then it will compile it into your library-output2.js file so you end up having duplicates of classes if you are trying to re-use typescript across multiple compiled targets (like how you would have 1 solution in VS and multiple projects which have their own dll outputs)
Assuming you are not happy with hacking the exports and/or duplicating your references then you can just import them into the global scope, which is a hack but works... however then when you decide you want to test your code (using whatever nodejs testing framework) you will need to mock out certain things, and as the dependencies for your components may not be included via a require() call (and your module may depend upon node_modules which are not really usable with global scope hacking) and this then makes it difficult to satisfy dependencies and mock certain ones, its like an all or nothing sort of approach.
Finally you can try to mitigate all these problems by using a typescript framework such as appex which allows you to run your typescript directly rather than the compile into js first, and while it seems very good up front it is VERY hard to debug compilation errors, this is currently my preferred way but I have an issue where my typescript compiles fine via tsc, but just blows up with a max stack size exception on appex, and I am at the mercy of the project maintainer to fix this (I was not able to find the underlying issue). There are also not many of these sort of projects out there however they make the issue of compiling at module level/file level etc a moot point.
Ultimately I have had nothing but problems trying to wrestle with Typescript to get it to work in a way which is maintainable and testable. I also am trying to re-use some of the typescript components on the clientside however if you go down the npm hack route to get your modules included you then have to make sure your client side uses a require compatible resource/package loader. As much as I would love to just use typescript on my client and my server projects, it just does not seem to want to work in a nice way.
Solution here:
Inheritance TypeScript with exported class and modules
Finally I don't use require-typescript but typescript.api instead, it works well. (You have to load lib.d.ts if you use it, else you'll get some errors on the console.
I don't have a solution to have the script on the browser yet. (Because of export keyword I have some errors client side) I think add a exports global var to avoid errors like this.
Thank you for your help Bill.
I'm using node.JS in VirtualBox on a TurnkeyLinux hosted by Windows. I was following the instructions here. node.JS is living in /root/node. Although I can run simple examples successfully I'm having a hard time figuring out certain things, cause I'm not a Linux-guy normally. I wanted to use socket.io.
I managed installing node.JS itself using git and tried that with Express and Socket.IO too. (e.g. git clone git://github.com/LearnBoost/Socket.IO.git). It seems to work, but I can't find that stuff anywhere! Was in /root/node when calling git, expecting changes in the lib-folder...
node.JS is using the CommonJS module system. In the Socket.IO example io = require('../') is used to import Socket.IO which looks pretty strange to me. Other expamples on the web are referring to './Socket.IO-node'. As a module is just a JS-file following certain rules I would expect sth like a path to such a file, as I found http.js in /root/node/lib.
By the way, looking at the server.js example: Is there a certain reason using var for http, but not for the rest of the variables (url, fs, io, sys)?
On clientside the first line on "How to use" Socket.IO is: io.setPath(...). setPath is not mentioned anywhere else on the page. Where should it point to, relative to what?
I've found no information about stoping/restarting node using the shell. Probably it's so obvious, that it's never mentioned anywhere ;)
Thanks for helping out.
The git-version that comes with the Turnkey-Core these days is quite outdated. Maybe this is causing problems. I worked around using my git on windows and WinSCP ;)
There is an inbuild automatism that index.js is used by default like index.html is used by default on webservers. So '../' is pointing to index.js in the parent folder, which then exports the listener of socket.io. Guillermo Rauch has put an index.js in the socket.io-folder now, so sth like './lib/socket.io/' is working. Note that there are examples out there with sth like './socket.io/socket.io.js', but socket.io.js doesn't exist anymore for some good reasons.
Of course the var is used for all variables. I've seen the commas as semicolons. Maybe I should change my screen-resolution ;)
It comes clear when looking at the example. setPath points to the folder where socket.io.js and it's lib-directory lives, relative to the html-file that uses it. This is needed for the flash-sockets to work.
Well, it's not that simple. You may look up the PID usind 'ps ux' and then 'kill' the process using the PID. A better way is using upstart. Or you do it by code using autorestart.