Webpack dark/light loader example

custom-loader.js

module.exports.pitch = function (remainingRequest) {
  const [fileName, ext] = remainingRequest.split('!').pop().split('.')
  const darkPictureRequest = '-!' + remainingRequest.replace(`${fileName}.${ext}`, `${fileName}-dark.${ext}`)
  const lightPictureRequest = '-!' + remainingRequest.replace(`${fileName}.${ext}`, `${fileName}-light.${ext}`)

  return `
    module.exports = {
      dark: require(${JSON.stringify(darkPictureRequest)}),
      light: require(${JSON.stringify(lightPictureRequest)})
    };
  `
}