Develop Reference

Error when typing "npm start" in visual studio using react.js

PS C:\Users\PC1\Downloads\portfolio_website-STARTER> npm start
> portfolio_website-starter#1.0.0 start C:\Users\PC1\Downloads\portfolio_website-STARTER
> node index.js
internal/modules/cjs/loader.js:892
throw err;
^
Error: Cannot find module 'C:\Users\PC1\Downloads\portfolio_website-STARTER\index.js'
at Function.Module._resolveFilename (internal/modules/cjs/loader.js:889:15)
at Function.Module._load (internal/modules/cjs/loader.js:745:27)
at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:76:12)
at internal/main/run_main_module.js:17:47 {
code: 'MODULE_NOT_FOUND',
requireStack: []
}
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! portfolio_website-starter#1.0.0 start: `node index.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the portfolio_website-starter#1.0.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm WARN Local package.json exists, but node_modules missing, did you mean to install?
npm ERR! A complete log of this run can be found in:
npm ERR! C:\Users\PC1\AppData\Roaming\npm-cache\_logs\2021-09-05T22_40_19_833Z-debug.log
PS C:\Users\PC1\Downloads\portfolio_website-STARTER>
The error shown above happens when I try to run npm start to start the virtual host.
I have tried the following:
Updated node.js to the latest version.
Went to package.json under scripts and added "start": "node index.js".

first, do you install the dependencies? (npm i)
Then, exists index.js file in the portfolio_website-STARTER folder?

First make sure your startup file is index.js in your package.json file and make sure you have index.js in your project.

Can't start webpack development server

I am new on es6. I followed a blog Beginner’s Guide To Setup ES6 Development Environment. I completed all of the process step-by-step. Then the step comes up to install the webpack development server. Then I write this code to cmd - npm run build. I get this error:
λ npm run build
-> jj#1.0.0 build C:\Users\galib\Desktop\jj
-> webpack-dev-server
The CLI moved into a separate package: webpack-cli
Please install 'webpack-cli' in addition to webpack itself to use the CLI
-> When using npm: npm i -D webpack-cli
-> When using yarn: yarn add -D webpack-cli
internal/modules/cjs/loader.js:888
throw err;
^
Error: Cannot find module 'webpack-cli/bin/config-yargs'
Require stack:
- C:\Users\galib\AppData\Roaming\npm\node_modules\webpack-dev-server\bin\webpack-dev-server.js
at Function.Module._resolveFilename (internal/modules/cjs/loader.js:885:15)
at Function.Module._load (internal/modules/cjs/loader.js:730:27)
at Module.require (internal/modules/cjs/loader.js:957:19)
at require (internal/modules/cjs/helpers.js:88:18)
at Object.<anonymous> (C:\Users\galib\AppData\Roaming\npm\node_modules\webpack-dev-server\bin\web
at Module._compile (internal/modules/cjs/loader.js:1068:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1097:10)
at Module.load (internal/modules/cjs/loader.js:933:32)
at Function.Module._load (internal/modules/cjs/loader.js:774:14)
at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:72:12) {
code: 'MODULE_NOT_FOUND',
requireStack: [
'C:\\Users\\galib\\AppData\\Roaming\\npm\\node_modules\\webpack-dev-server\\bin\\webpack-dev-serv
]
}
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! jj#1.0.0 build: `webpack-dev-server`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the jj#1.0.0 build script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
npm ERR! A complete log of this run can be found in:
npm ERR! C:\Users\galib\AppData\Roaming\npm-cache\_logs\2021-06-08T18_22_59_337Z-debug.log

The article you read was probably written before Webpack's cli was moved to webpack-cli, so you might need one small extra step.
Please install 'webpack-cli' in addition to webpack itself to use the CLI
-> When using npm: npm i -D webpack-cli
-> When using yarn: yarn add -D webpack-cli
Run npm i -D webpack-cli and then you can use the Webpack CLI.

How to fix nodemon "block-scoped declarations..." error?

This is my package.json file:
{
"name": "pro-mern-stack",
"version": "1.0.0",
"description": "first init",
"main": "index.js",
"scripts": {
"start": "nodemon server.js server.js",
"compile": "babel src --presets react,es2015 --out-dir static",
"watch": "babel src --presets react,es2015 --out-dir static --watch",
"test": "echo \"Error: no test specified\" && exit 1"
},
"author": "Yusuf",
"license": "ISC",
"dependencies": {
"body-parser": "^1.19.0",
"express": "^4.17.1",
"mongodb": "latest"
},
"devDependencies": {
"express": "^4.17.1",
"nodemon": "^2.0.2"
}
}
I'M TRYING TO RUN npm start TO START THE WATCHER BUT I KEEP GETTING THIS ERROR:
> nodemon server.js server.js
C:\MERN\pro-mern-stack\node_modules\nodemon\lib\monitor\run.js:356
let sig = signal.replace('SIG', '');
^^^
SyntaxError: Block-scoped declarations (let, const, function, class) not yet supported outside strict mode
at exports.runInThisContext (vm.js:53:16)
at Module._compile (module.js:373:25)
at Object.Module._extensions..js (module.js:416:10)
at Module.load (module.js:343:32)
at Function.Module._load (module.js:300:12)
at Module.require (module.js:353:17)
at require (internal/module.js:12:17)
at Object.<anonymous> (C:\MERN\pro-mern-stack\node_modules\nodemon\lib\monitor\index.js:2:8)
at Module._compile (module.js:409:26)
at Object.Module._extensions..js (module.js:416:10)
npm ERR! Windows_NT 10.0.10240
npm ERR! argv "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js" "start"
npm ERR! node v4.5.0
npm ERR! npm v2.15.9
npm ERR! code ELIFECYCLE
npm ERR! pro-mern-stack#1.0.0 start: `nodemon server.js server.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the pro-mern-stack#1.0.0 start script 'nodemon server.js server.js'.
npm ERR! This is most likely a problem with the pro-mern-stack package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR! nodemon server.js server.js
npm ERR! You can get information on how to open an issue for this project with:
npm ERR! npm bugs pro-mern-stack
npm ERR! Or if that isn't available, you can get their info via:
npm ERR!
npm ERR! npm owner ls pro-mern-stack
npm ERR! There is likely additional logging output above.
npm ERR! Please include the following file with any support request:
npm ERR! C:\mern\pro-mern-stack\npm-debug.log
I'm running with powershell on windows 10. I've tried installing globally, didn't work. Also have the latest version of nodemon. Please, how can i fix this? I've reinstalled nodemon several times, keep getting the same error, even when I run it directly in the console. Thanks!

I see issue in the npm script. You should just update it to nodemon server.js

react-scripts start error (Cannot find module '../scripts/start') - how can i fix this?

I'm getting 'Error: Cannot find module '../scripts/start' from projects set up using create-react-app that previously worked fine, now when i run 'npm start' i'm getting this error - the only workaround seems to be rm -rf node_modules followed by npm install, but next day I run into the same problem. Any ideas how to fix this please (see full error message below) - thanks.
>react-scripts start
module.js:549
throw err;
^
Error: Cannot find module '../scripts/start'
at Function.Module._resolveFilename (module.js:547:15)
at Function.resolve (internal/module.js:18:19)
at Object.<anonymous> (/Users/DANTHORY/Dropbox/card-slider-challenge_TESTING/node_modules/.bin/react-scripts:28:25)
at Module._compile (module.js:652:30)
at Object.Module._extensions..js (module.js:663:10)
at Module.load (module.js:565:32)
at tryModuleLoad (module.js:505:12)
at Function.Module._load (module.js:497:3)
at Function.Module.runMain (module.js:693:10)
at startup (bootstrap_node.js:191:16)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! card-slider-challenge#0.1.0 start: `react-scripts start`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the card-slider-challenge#0.1.0 start script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
package.json:
{
"name":"card-slider-challenge",
"version":"0.1.0",
"private":true,
"scripts":{
"start":"react-scripts start",
"build":"react-scripts build",
"test":"jest",
"eject":"react-scripts eject",
"start-api":"json-server --port 3001 --watch --static none data/db.json"
},
"dependencies":{
"react":"^16.3.2",
"react-dom":"^16.3.2",
"react-slick":"^0.23.2"
},
"devDependencies":{
"jest":"^24.0.0",
"json-server":"^0.12.2",
"react-scripts":"^1.1.4"
}
}

I had the exact same issue and I did the following:
Delete node_modules folder
Run npm install
It fixed my issue, but what it caused, I don't know.

I changed my computer and I clone my projet from Github
Delete node_modules folder
Run npm install

Error when running "npm start"?

I have started with electron today and followed a guide to create a simple application browser window and I ran npm start in the command window and it displayed a lot of errors after I had entered it, I have posted the information below and my code.
Console error:
C:\Users\Administrator\Desktop\electron>npm start
> breef#1.0.0 start C:\Users\Administrator\Desktop\electron
> node index.js
module.js:471
throw err;
^
Error: Cannot find module 'app'
at Function.Module._resolveFilename (module.js:469:15)
at Function.Module._load (module.js:417:25)
at Module.require (module.js:497:17)
at require (internal/module.js:20:19)
at Object.<anonymous> (C:\Users\Administrator\Desktop\electron\index.js:1:73)
at Module._compile (module.js:570:32)
at Object.Module._extensions..js (module.js:579:10)
at Module.load (module.js:487:32)
at tryModuleLoad (module.js:446:12)
at Function.Module._load (module.js:438:3)
npm ERR! Windows_NT 10.0.14393
npm ERR! argv "C:\\Program Files\\nodejs\\node.exe" "C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js" "start"
npm ERR! node v6.9.2
npm ERR! npm v3.10.9
npm ERR! code ELIFECYCLE
npm ERR! breef#1.0.0 start: `node index.js`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the breef#1.0.0 start script 'node index.js'.
npm ERR! Make sure you have the latest version of node.js and npm installed.
npm ERR! If you do, this is most likely a problem with the breef package,
npm ERR! not with npm itself.
npm ERR! Tell the author that this fails on your system:
npm ERR! node index.js
npm ERR! You can get information on how to open an issue for this project with:
npm ERR! npm bugs breef
npm ERR! Or if that isn't available, you can get their info via:
npm ERR! npm owner ls breef
npm ERR! There is likely additional logging output above.
npm ERR! Please include the following file with any support request:
npm ERR! C:\Users\Administrator\Desktop\electron\npm-debug.log
Here is my package.json:
{
"name": "breef",
"version": "1.0.0",
"description": "A simple chat application.",
"main": "index.js",
"dependencies": {
"electron": "^1.4.12"
},
"devDependencies": {},
"scripts": {
"test": "breeftestcmd",
"start": "node index.js"
},
"keywords": [
"breef"
],
"author": "Sage & Sh4wn",
"license": "ISC"
}
Here is my index.js:
var app = require("app")
var browserWindow = require("browser-window")
app.on('ready', function() {
var mainWindow = new browserWindow({
width: 800,
height: 600
})
mainWindow.loadUrl('http://google.com');
})

If app is a module, it's missing in your package.json. If not, you should use a path to require it
var app = require('./app');

The guide you followed is out of date, as of Electron v1.0.0 the way built-in Electron modules are imported has changed. This is the correct way:
const {app, BrowserWindow} = require("electron")
You may also find it beneficial to read the previous question that covered this topic: What's the proper way to require in Node.js?