old_contents: // welcome.js
  
  "use strict";
  
  function welcome(message) {
    if (NODE_ENV == "development") {
      debugger;
    }
  
    alert(`Welcome ${message}`);
  }
  
  export { welcome };
  
new_contents: // welcome.js
  
  "use strict";
  
  function welcome(message) {
    if (NODE_ENV == DEV_ENV) {
      debugger;
    }
    console.log(`Welcome ${message}`);
  
    alert(`Welcome ${message}`);
  }
  
  export { welcome };
  
subject: Use DEV_ENV. Add console.log for testing UglifyJS