text: const PREFIX = /^NUSWHISPERS_/i;
  
  // Adapted from create-react-app.
  module.exports = function createClientEnvironment(env) {
    const processEnv = Object
      .keys(env)
      .filter(key => PREFIX.test(key))
      .reduce((e, key) => {
        e[key] = env[key]; // eslint-disable-line no-param-reassign
        return e;
      }, {
        NODE_ENV: env.NODE_ENV || 'development',
        VUE_ENV: env.VUE_ENV || 'client',
      });
  
    return {
      'process.env': Object
        .keys(processEnv)
        .reduce((e, key) => {
          e[key] = JSON.stringify(processEnv[key]); // eslint-disable-line no-param-reassign
          return e;
        }, {}),
    };
  };
  