text: // Grab NODE_ENV and REACT_APP_* environment variables and prepare them to be
  // injected into the application via DefinePlugin in Webpack configuration.
  
  var REACT_APP = /^REACT_APP_/i;
  
  function getClientEnvironment(publicUrl) {
    var processEnv = Object
      .keys(process.env)
      .filter(key => REACT_APP.test(key))
      .reduce((env, key) => {
        env[key] = JSON.stringify(process.env[key]);
        return env;
      }, {
        // Useful for determining whether we’re running in production mode.
        // Most importantly, it switches React into the correct mode.
        'NODE_ENV': JSON.stringify(
          process.env.NODE_ENV || 'development'
        ),
        
        // Useful for resolving the correct path to static assets in `public`.
        // For example, <img src={process.env.PUBLIC_URL + '/img/logo.png'} />.
        // This should only be used as an escape hatch. Normally you would put
        // images into the `src` and `import` them in code to get their paths.
        'PUBLIC_URL': JSON.stringify(publicUrl)
      });
    return {'process.env': processEnv};
  }
  
  module.exports = getClientEnvironment;
  