ESLint demo

ESLint is a lint checker for javascript.

Using Online

You can use the tool online at https://eslint.org/demo to test your code and play with configuration options. There is an option at the bottom of the screen to download the configuration file afterward.

Use Programmatically

1. Install NodeJS version 14 https://nodejs.org/en/download/.

2. If you are on Mac or Linux, you will need to update where NodeJS stores packages using the command line. Follow the instructions here https://docs.npmjs.com/resolving-eacces-permissions-errors-when-installing-packages-globally to change the location. Below is a script you can run in the terminal.

   npm config set prefix '~/.npm-global'
   echo 'export PATH=~/.npm-global/bin:$PATH' >> ~/.profile
   source ~/.profile

3. Update npm (Node Package Manager) on your computer.

   npm install -g npm@latest

4. Install the eslint package globally.

   npm instal -g eslint

5. Install the ESLint vscode extension. You can search for the extension using this identifier dbaeumer.vscode-eslint. Microsoft maintains this extension, so it should be pretty safe.

Project Structure

Create a.eslintrc.json or .eslintrc.js in your root directory where you plan on storing your project files.

If set up correctly, you will see the red squiggly lines in your editor, and when you hover over the error, it should tell you if it is a lint error. ESLint can fix specific errors automatically, for example, missing semi-colons.

You can run eslint on the command line.

# check files in the current directory
eslint .

# check files in the current directory and fix if possible.
eslint --fix .

About

ESLint is one of the most popular lint checkers and has a solid open source community. The source code is on GitHub.