React JS npm start shows failed to compile web-vitals

Question

I'm getting the error:

failed to compile -/src/reportWebVitals.js Module not found: Can't resolve 'web-vitals'. Since new to react JS, could not find what happened. Here is the reportWebVitals.JS file. Thanks in advance for the help. "/src/reportWebVitals.js Module not found: Can't resolve 'web-vitals' in 'E:\ReactResources\RectProjects\test-app\src'"

const reportWebVitals = onPerfEntry => {
if (onPerfEntry && onPerfEntry instanceof Function) {
import('web-vitals').then(({ getCLS, getFID, getFCP, getLCP, getTTFB }) => {
  getCLS(onPerfEntry);
  getFID(onPerfEntry);
  getFCP(onPerfEntry);
  getLCP(onPerfEntry);
  getTTFB(onPerfEntry);
});
}};
export default reportWebVitals;

Answer 1

You need to install web vitals. Open your terminal and run the following command:

npm i web-vitals --save-dev

Also, deleting the whole thing and reinstalling might work, but that's a longer process.

Answer 2

For anyone coming here from starting a brand new app with create-react-app : If you are using npm but run create-react-app without explicitly specifying it, it will use yarn when available. I was able to bypass this issue by adding the flag --use-npm .

So, for example:

npx create-react-app my-app --use-npm

Source

Answer 3

failed to compile -/src/reportWebVitals.js Module not found: Can't resolve 'web-vitals'. Since new to react JS, could not find what happened. Here is the reportWebVitals.JS file. Thanks in advance for the help.

"/src/reportWebVitals.js Module not found: Can't resolve 'web-vitals' in 'E:\ReactResources\RectProjects\test-app\src'"

const reportWebVitals = onPerfEntry => {
if (onPerfEntry && onPerfEntry instanceof Function) {
import('web-vitals').then(({ getCLS, getFID, getFCP, getLCP, getTTFB }) => {
  getCLS(onPerfEntry);
  getFID(onPerfEntry);
  getFCP(onPerfEntry);
  getLCP(onPerfEntry);
  getTTFB(onPerfEntry);
});
}};
export default reportWebVitals;

Answer 4

for me following worked
first do npm uninstall react-scripts
then do npm install react-scripts

Answer 5

Delete all the files & Folders inside test-app folder. Reinstall all the packages now and start npm. It will work.

Answer 6

failed to compile -/src/reportWebVitals.js Module not found: Can't resolve 'web-vitals'. Since new to react JS, could not find what happened. Here is the reportWebVitals.JS file. Thanks in advance for the help.

"/src/reportWebVitals.js Module not found: Can't resolve 'web-vitals' in 'E:\ReactResources\RectProjects\test-app\src'"

const reportWebVitals = onPerfEntry => {
if (onPerfEntry && onPerfEntry instanceof Function) {
import('web-vitals').then(({ getCLS, getFID, getFCP, getLCP, getTTFB }) => {
  getCLS(onPerfEntry);
  getFID(onPerfEntry);
  getFCP(onPerfEntry);
  getLCP(onPerfEntry);
  getTTFB(onPerfEntry);
});
}};
export default reportWebVitals;

Answer 7

If you have created your project with create-react-app , all the dependencies should be there when you run npm install .

Make sure you did that by navigating to the root directory and running:

npm install

Answer 8

I closed my terminal and opened again. Works for me!