Babel is a JavaScript compiler. This is how to set it up in a project.
In the terminal, cd into the project directory. Then, you need to create a package.json via:
npm init
Now it's time to install the Babel.js core and CLI libaries:
npm install --save-dev @babel/core @babel/cli
Optional. Install the plugin-proposal-class-properties plugin:
npm install --save-dev @babel/plugin-proposal-class-properties
Compile the entire src directory and output it to the lib directory by using either --out-dir or -d. This doesn't overwrite any other files or directories in lib.
npx babel src --out-dir lib
Compile the entire src directory and output it as a single concatenated file.
npx babel src --out-file script-compiled.js
To compile a file every time that you change it, use the --watch or -w option:
npx babel script.js --watch --out-file script-compiled.js
Use the --plugins option to specify plugins to use in compilation:
npx babel script.js --out-file script-compiled.js --plugins=@babel/proposal-class-properties,@babel/transform-modules-amd
Use the --presets option to specify presets to use in compilation
npx babel script.js --out-file script-compiled.js --presets=@babel/preset-env,@babel/flow
© 2025 by Ryan Rickgauer