I just started studying front-end development and I'm struggling with a node.js error.
Typing 'npm start' in my VSCode terminal used to work fine for simple tutorial projects with just an index.html, script.js, and style.css file. (without a package.json file)
However after trying out React for the first time, 'npm start' now doesn't work anymore in my other non-React projects. At first it was giving me an error that it was missing the package.json (which it didn't need before?) but after trying to fix it with help of googling I now got to a point where it's giving me the error: Missing script: "start".
How can I run node without creating package.json files for every small tutorial project I've made previously, or without turning them into React apps? Also why is this happening? Did installing React-native create dependencies of some sort?
Thanks in advance!
I already tried reinstalling node.js and tried different versions. Also tried deleting package-lock.json. It still works for React apps, just not with simpler native javascript apps.
A package.json file is required if you want to install any packages or run scripts in your terminal. In your package.json file, make sure you have added scripts property. This is an example of how you can use it:
{
...
"scripts": {
"start": "react-scripts start"
}
}
Remove ... from the snippet if you're copying, this has been added to indicate that there are one or more fields in this JSON file.
After you have added this to your package file, you will be able to run the start script by typing npm run start in the terminal or if you use Yarn: yarn start.
Edit:
You said that running npm start in your React project is running fine, but on your simpler projects with only a simple HTML, CSS and JS file is not working when using the script.
You are probably confusing npm start with node file.js. Where node file.js doesn't require a package to be in your project to run a JavaScript file, using npm start requires you to have a JSON file present in your project folder with the JSON code as in my answer.
So long story short: Using npm start requires package.json with the script property available. While node file.js doesn't require you to have this file in your project.
if you are using react-native you can do the following
First you have to build your project with the command
npx react-native run-android , npx react-native run-ios
Once your project has build successfully and app is installed on your device then you your development server is started already. for some reason if your server is closed then you can run it with the command given below.
adb reverse tcp:8081 tcp:8081 this will send a signal to your device and after this run npx react-native start
Related
I've been trying to run this code that brings up an electron GUI and takes input from the user. I I've used the following commands to run this project in VSCode powershell terminal:
npm install
npm start
I get the following error messages in the terminal afterwards:
Error Message 1
Error Message 2
Error Message 3
I've already checked that I have the most updated packages for nodejs, npm, electron, electron-packager and electron-builder. You can see the last three in my package.json file under the devDependencies.
Package.json dev dependencies and scripts
I don't really understand what the error is saying here. From the googling I've done, it seems like this happens on WSL when you're trying to launch an electron application but I'm working off of my local machine on Windows, so I wouldn't think that a GUI should throw an error.
I can run main.js by using electron.cmd main.js but this just brings up the GUI splash from electron but the code itself doesn't seem to be executing.
The answer in my case was switching to use Yarn instead of npm. Clearing the node modules folder and running yarn install and running election ./app from the main project folder.
I am brand new to React and NodeJS. I have NodeJS latest version installed on my mac as well as React. I can start and run the app using npm start I am following tutorials and it was fine and I could see my app in the browser. The problem begins when I need to finish for the day and start again the next day and I do not know how to start the server again and app and to continue the work. npm start does not work. Unfortunately tutorials only show how to start the app for the very first time, but they don't show what do you need to do to interrupt your work, shut down computer and continue the following day. What steps do I need to take in to continue my work the following day?
regarding your question the things you want to make sure that whatever project you are working on (nodejs or react) that you cd into the project folder before you run any commands as these scripts you are running "npm run start" etc.. are based on what scripts are written inside the package.json.
so if you use create-react-app for reactjs the "npm run start" is a default script that comes with CRA and will run the app for you.
for express you can also check the scripts and there will be something similar but you can do "node server.js" (or app.js depends on how you called the file you initialize the server) and it will run the server.
in summary:
make sure to cd into the correct directory
check package.json for scripts if you are not sure what they are
also run "npm install" as you might have some missing dependencies
enjoy.
If you have any more questions will edit my response to answer those as well, have a nice day ;)
Just look for error messages in the Terminal when you run npm start. Try to understand them and fix them.
You can also install Nodemon (npm i nodemon) and run nodemon {filename}.js to start the server. {filename} is the name of the file in which you're starting the server.
I created my own npm package from a fork of react-coverflow. It appears to be working fine in my app locally using it this way: "npm install react-coverflow-mod" --save.
I can run my app using "run with debug (F5)" in VsCode and npm start on the client folder to start the React front end.
Then I do an npm run build on the client folder, and it works just fine.
When I do a heroku push it fails everytime with this error:
npm ERR! code ENOLOCAL
npm ERR! Could not install from "../../react-coverflow-mod"
as it does not contain a package.json file.
1. I know there is a package.json in the module because I can install it via "npm install react-coverflow-mod": https://www.npmjs.com/package/react-coverflow-mod
2. The installed module has a package.json file in it
3. My github repo has a package.json in it: https://github.com/leroyvaughan/react-coverflow
I'm not sure how I can fix this. Do I need a package.json to go into the /Dist folder? What is wrong here with Heroku.
It seams like heroku try to install a package from a relative path instead of the published name. That would perfectly explain why you can run locally but not on a production environment.
Open your project and search for the exact string displayed in your log: "../../react-coverflow-mod" and you should be able to find quickly where it is.
If you run on a unix system (don't know about windows) you can do a search using grep:
grep -rnw '/path/to/somewhere/' -e '../../react-coverflow-mod'
Make sure it includes your root folder which contain package.json, and might we wise to ignore node_modules which is always massive.
I'm reading node js code wherein package.json I found the following script
scripts: {
start : 'some-dependency start'
}
So, when I run npm run start it's actually starting my application with a web server, serving static files in my project.
My question is how some-dependency start running? what it can do? how it can serve my static files. I see internally some-dependency using react-scripts. But I can't wrap my head around how all these things working.
react-scripts is a package that comes in built with create-react-app when you run npm run start it executes a script/program that is wrapped in react-scripts package you can see the script for start command here, in that you can see that the script invokes the webpack-dev-server which serves the bundled javascript on a server
Generally when you execute some script through package.json file the same happens, you need to specify a command/ invoke a script
for example consider following script present in package.json file
script: {
"development": " cd client/ && NODE_ENV=development webpack -w --config webpack.dev.config.js"
}
In the above example when you run npm run development the following things happen
changes the directory to client
Node environment is set to development
invokes the webpack with the config file webpack.dev.config.js present in the client directory
It executes what ever that is written in the config file
Feel free to ask doubts if any
I am going to create an app which deals with Angular5(front-end), Nodejs(middle-end) and MongoDB(back-end).
Below is the folder structure:
Package.json: "start": "ng build & node server.js"
Now when I am start the app by npm start, It throws the following error:
"Unable to find any apps in .angular-cli.json."
I hope node server is looking for this file to load angular codes. But it lies inside angular folder.
If I place both angular and node codes in same place, it works well.
But it looks more clumsy and a bit confusing. I don't want to compromise with my folder structure.
Can anyone please help to achieve the app working on the same folder structure that I would prefer?
Thanks in advance.
it might be that your global #angular/cli installation got corrupt. You may try a cache clean and reinstall..
npm cache clean
npm -g i #angular/cli
If you use angular cli for creating the project, then looks something wrong in the package.json, (as I seen your comment on the previous answer)
first uninstall angular cli if already install by using
npm uninstall -g #angular/cli, then npm install -g #angular/cli after cli installation ng new [project name /folder name]
cd [project name /folder name]
ng serve --open
try once.
I got this same error in my current project and was confused because I'm running the application / ng serve in one terminal, but got this when I tried to generate a component from another terminal. .angular-cli.json was already there and correct. So what gives?
I realized that I used the shortcut to open VisualStudio Code's internal terminal -- which opened the terminal to the *root of the project * (like most IDEs). The project contains other things in addition to the Angular application folder that has the .angular-cli.json file in question. I just had to cd to the right folder and run ng g c again and things were fine.
In my case it was just a silly error. I thought I'd come back to share in order to save people a real headache for something so simple. I see that Shiva actually has mentioned this above, but I thought I would give a bit more detail so it doesn't get overlooked.
Reference URL: How to generate .angular-cli.json file in Angular Cli?