I am using ExpressJS and would like to display internal debug messages, like here https://expressjs.com/en/guide/debugging.html.
When I am using this command in VS Code (Windows Powershell) "`set DEBUG=express:*; node ./dist/app.js" it is starting my Node/Express Server, however it does not display any debug messages. Do I have to add something to my code so it works?
"Express uses the debug module internally to log information about route matches, middleware functions that are in use, application mode, and the flow of the request-response cycle."
Do you have this package:
https://www.npmjs.com/package/debug
And there is no semicolon between the statements.
I tried the same in windows command prompt and it worked there just exchanged the semicolon for an ampersand.
set DEBUG=express:* & node ./dist/app.js
Related
We have an install of Node.js running on a Windows Server 2012R2 web server. A developer created an application for us using Next/React/Node (I'm not a web developer so I'm unsure of the specifics of the various development tools used). This app works fine when manually started on the command line like this:
C:\NodeApps\pacifield>"C:\PROGRAM FILES\NODEJS\NODE.EXE" C:\NodeApps\pacifield\node_modules\next\dist\bin\next start
However this requires someone to manually login and restart the app whenever the server is rebooted or the app stops for whatever reason. I am trying to setup PM2 to run the app. I have it up and running fine until you browse to the app - at which point you get the following error:
next-server.ts:306 Error: Invalid hook call. Hooks can only be called inside of the body of a function component. This could happen for one of the following reasons:
1. You might have mismatching versions of React and the renderer (such as React DOM)
2. You might be breaking the Rules of Hooks
3. You might have more than one copy of React in the same app
See https://reactjs.org/link/invalid-hook-call for tips about how to debug and fix this problem.
at resolveDispatcher (c:\NodeApps\pacifield\node_modules\react\cjs\react.development.js:1476:13)
at useContext (c:\NodeApps\pacifield\node_modules\react\cjs\react.development.js:1484:20)
at useSession (c:\NodeApps\pacifield\node_modules\next-auth\dist\client\index.js:75:39)
at Provider (c:\NodeApps\pacifield\node_modules\next-auth\dist\client\index.js:588:12)
at processChild (C:\NodeApps\pacifield\node_modules\react-dom\cjs\react-dom-server.node.development.js:3353:14)
at resolve (C:\NodeApps\pacifield\node_modules\react-dom\cjs\react-dom-server.node.development.js:3270:5)
at ReactDOMServerRenderer.render (C:\NodeApps\pacifield\node_modules\react-dom\cjs\react-dom-server.node.development.js:3753:22)
at ReactDOMServerRenderer.read (C:\NodeApps\pacifield\node_modules\react-dom\cjs\react-dom-server.node.development.js:3690:29)
at Object.renderToString (C:\NodeApps\pacifield\node_modules\react-dom\cjs\react-dom-server.node.development.js:4298:27)
at Object.renderPage (C:\NodeApps\pacifield\node_modules\next\dist\server\render.js:596:45)
I have checked and there is only the one installation of React in C:\NodeApps\pacifield\node_modules\react and the other suggestions don't seem to make sense when it runs fine outside of PM2. I have checked with ProcessExplorer that all the environment variables are the same (except for the additional ones PM2 adds) when the app is run from the command line vs. PM2.
Anyone have any suggestions?
Hooks can only be call inside of functional component or inside another hook.
take note: Invalid Hook Call Warning
Notify your frontend developer it.
I'm wondering if it's possible to use command line arguments with ReactJS (not react-native). For example, is it possible to input a simple string and have it be saved as a variable so it can be displayed? The npm yargs module is the kind of thing I'm looking for, but I couldn't get that to work because the child process it spawns apparently doesn't work in a browser.
Edit: I've also tried something like including {process.argv[0]} in say an h1 tag, but nothing shows up.
React doesn't have anything special for command line arguments. In fact, it is primarily designed as a DOM library. You could use yargs and then pass the values to a React component.
For example you run this command in terminal or cmd
npm start -- foo
foo is your argument.
You can print your like this
// print process.argv
process.argv.forEach(function (val, index, array) {
console.log(index + ': ' + val);
});
in your script.
React runs is client-side
React is a client-side library. It runs in a web page, on a browser. The end-user doesn't use the command-line to "run" React, therefore command-line arguments are not available to the end-user.
For developers
As a developer, you do use tools to start a development server and launch a browser that is running React. Most likely, you're using Create React App. You can use environment variables to pass variables/arguments to React. Specifically, the documentation offers these examples:
# on Linux and macOS
REACT_APP_NOT_SECRET_CODE=abcdef npm start
# on Windows (cmd.exe)
set "REACT_APP_NOT_SECRET_CODE=abcdef" && npm start
Note that these variables are embedded into React at build time, when Create React App bundles and builds your app (kind of like compiling). This means that if you build your React project and then transfer the output files to another server and try to pass new variables, nothing will change.
For servers
If your React build files are on a server and you want to be able to pass command-line arguments to the server and have React change, this is also possible, but largely depends on what software you are using to serve. Broadly, the server would take the runtime argument and pass it into the template which renders your React app. Then any Javascript that runs on that page can access the arguments.
I am working on an application for Audio/Video calls using easyrtc.
I have added turn server details in server.js file to configure the turn servers I want to use.
var myIceServers = [
{url: "stun:stun.anyfirewall.com:3478"},
{url: "turn:turn.anyfirewall.com:443", "username":"xxxxx", "credential":"xxxxx"},
{url: "turn:turn.anyfirewall.com:443?transport=tcp", "username":"xxxxx", "credential":"xxxxx"}
];
then set options for appIceServers using below line of code.
easyrtc.setOption("appIceServers", myIceServers);
and configured the listener as well.
easyrtc.on("getIceConfig", function(connectionObj, callback){
callback(null, myIceServers);
}
After this when I am running easyrtc simple audio-video demo, from local machine, in chrome using two tabs it works fine.
Now I have two questions:
How do I make sure that easyrtc is using custom supplied TURN server configuration ?
And from where I need to test the links for my application, which will make sure that easyrtc is using custom supplied TURN url for tcp ? (i.e. firewall check).
You can turn the "log level" to "3" in server.js to see more detail logs, and use chrome://werbrtc-internals to see the chrome webrtc logs . I just set up a TURN server yesterday and in my way , I modified the easyrtc_default_options to using my own TURN,I think your configuration will work if you test with two client in different network, the Turn server will give you a feedback.
"from local machine, in chrome using two tabs it works fine." this is not using you TURN server.
I use Yeoman to do some angular development with grunt, livereload etc.
I've also set up a basic node.js/express app and I'm sharing some JS between the client (angular) and the server (node) using grunt-contrib-copy and grunt-express-server that fires on every file-save using watch. So far so good!
The problem is if I introduce a syntax error into the code that I want to share with node and hit save. The syntax error gets shown in the log and breaks/stops the watch. Then I have to go restart the watch in the console by doing $ ctrl+c and $ grunt server.
Is there a way to get grunt-express-server not to break/stop the watch that's going on if a syntax error is found in the js code?
I'm the author of grunt-express-server and working the issue here:
https://github.com/ericclemmons/grunt-express-server/issues/27
I've been able to work around this problem by running grunt-parallel or grunt-concurrent, which prevents errors from preventing execution of watch.
I'm looking for a way to output Node variables directly into the google chrome browser console. The same way a console.log() works on the client side. Something like this for php. This would greatly speed up development.
NOTE:
Since the old answer (written in september 2014) refers to an older version of node-inspector, my instructions are not relevant anymore in 2017. Also, the documentation has gotten a lot better, so I have updated my original answer:
node-inspector is what you need.
It opens up an instance of Chrome with its developer tools for debugging.
It's also easy to use:
1. Install
$ npm install -g node-inspector
2. Start
$ node-debug app.js
Source: https://github.com/node-inspector/node-inspector
You might want to try NodeMonkey - https://github.com/jwarkentin/node-monkey
I know it's an old question but came on top of my Google search so maybe somebody will find my answer useful.
So you can use node --inspect-brk index.js
Now, all you have to do is basically just type chrome://inspect in your Chrome address bar and click Open dedicated DevTools for Node
In DevTools, now connected to Node, you’ll have all the Chrome DevTools features you’re used to:
Complete breakpoint debugging, stepping w/ blackboxing
Source maps for transpiled code
LiveEdit: JavaScript hot-swap evaluation w/ V8
Console evaluation with ES6 feature/object support and custom object formatting
Sampling JavaScript profiler w/ flamechart
Heap snapshot inspection, heap allocation timeline, allocation profiling
Asynchronous stacks for native promises
Hope that helped.
The closest thing to this I've seen is Node JS console object debug inspector
See this post for usage and potential issues: http://thomashunter.name/blog/nodejs-console-object-debug-inspector/
For users with nodejs on linux via ssh-shell (putty):
Problem with nodejs on linux-ssh-shell is, that you have no browser connected.
I tried all this solutions, but didnt get it to work.
So i worked out a solution with firebase (https://firebase.google.com), because my project uses firebase.
If you are familiar with firebase, than this is a great way. If not, firebase is worth using in combination with nodejs - and its free!
In the server-side-script (started with node) use a own function log():
// server-side:
// using new firebase v3 !
var fbRootRef = firebase.database();
var fbConsoleRef = fbRootRef.ref("/console");
var log = function(args) {
fbConsoleRef.set({'obj': args});
}
// inside your server-code:
log({'key':'value'});
On client-side you create a firebase-reference on this console-object:
// client side:
fbRootRef.child('/console').on('value', function(d) {
var v = d.val();
console.log(v);
});
Now everything logged on server-side with the log() - function is transferred in realtime to the firebase-database and from there triggering the client-console-reference and logged into the browsers console.
If anyone needs help, i will explain in more detail and could give a more extended version of this logging with types (console./log/warn/info), grouping with title-info (i.e. server says: (filename + line).
Setting up firebase for your project is done in max 30 minutes, inserting the console-function in 30 minutes. I think its worth the time!
You can use bonsole, a simple way to log something in browser. Even in Linux, you can go to the LAN's ip to check it.
The most simple way with least dependencies is using a WebSocket connection to send the messages to the browser. Any WebSocket example you can find on the internet will suffice to accomplish this. Everything else requires to be heavily integrated into the host system and wouldn't work if you want to actually run this on a remote server. You can also send commands to the server directly from the browser console this way.
Links:
https://www.npmjs.com/package/websocket
https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_client_applications