What do “module.exports” and “exports.methods” mean in NodeJS / Express?

by

To be more specific:

module is the global scope variable inside a file.

So if you call require("foo") then :

// foo.js
console.log(this === module); // true

It acts in the same way that window acts in the browser.

There is also another global object called global which you can write and read from in any file you want, but that involves mutating global scope and this is EVIL

exports is a variable that lives on module.exports. It’s basically what you export when a file is required.

// foo.js
module.exports = 42;

// main.js
console.log(require("foo") === 42); // true

There is a minor problem with exports on it’s own. The _global scope context+ and module are not the same. (In the browser the global scope context and window are the same).

// foo.js
var exports = {}; // creates a new local variable called exports, and conflicts with

// living on module.exports
exports = {}; // does the same as above
module.exports = {}; // just works because its the "correct" exports

// bar.js
exports.foo = 42; // this does not create a new exports variable so it just works

Read more about exports

More Related Contents:

  1. What is the most efficient medium for both Node.js and Javascript to read and write a file?
  2. Error: Can’t set headers after they are sent to the client
  3. How to properly reuse connection to Mongodb across NodeJs application and modules
  4. Node.js global variables
  5. SyntaxError: Unexpected token function – Async Await Nodejs
  6. How do you send images to node js with Axios?
  7. SyntaxError: expected expression, got ‘
  8. using AngularJS html5mode with nodeJS and Express
  9. Why cant I inline call to res.json?
  10. TypeScript import/as vs import/require? [duplicate]
  11. Running multiple Node (Express) apps on same port
  12. Uncaught ReferenceError: process is not defined
  13. How to get updated document back from the findOneAndUpdate method?
  14. How to close electron app via javascript?
  15. Loop through asynchronous request
  16. Can I determine if a string is a MongoDB ObjectID?
  17. ES6+ javascript module export options
  18. Does every object in JS have a toString() method?
  19. how to get request path with express req object
  20. MissingSchemaError: Schema hasn’t been registered for model “User”
  21. Using Express Handlebars and Angular JS
  22. Calling Express Route internally from inside NodeJS
  23. Piping remote file in ExpressJS
  24. multer – req.file always undefined
  25. how to use jQuery installed with npm in Express app?
  26. Sessions won’t save in Node.js without req.session.save()
  27. How can I easily get access to form data in Express js?
  28. Changing a buffer from a ReadStream into an actual file
  29. How to structure a express.js application?
  30. Node JS fs module inside browser

Leave a Comment