Can't resolve module (not found) in React.js

The way we usually use import is based on relative path.

. and .. are similar to how we use to navigate in terminal like cd .. to go out of directory and mv ~/file . to move a file to current directory.

my-app/  node_modules/  package.json  src/    containers/card.js    components/header.js    App.js    index.js

In your case, App.js is in src/ directory while header.js is in src/components. To import you would do import Header from './components/header'. This roughly translate to in my current directory, find the components folder that contain a header file.

Now, if from header.js, you need to import something from card, you would do this. import Card from '../containers/card'. This translate to, move out of my current directory, look for a folder name containers that have a card file.

As for import React, { Component } from 'react', this does not start with a ./ or ../ or / therefore node will start looking for the module in the node_modules in a specific order till react is found. For a more detail understanding, it can be read here.

If you create an application with react-create-app, don't forget set environment variable:

NODE_PATH=./src

Or add to .env file to your root folder;

Deleted the package-lock.json file & then ran

npm install

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