How to use function before initializing within module.exports

I have two functions the first is register which uses a function called emailExists and both functions are exported using

// services.js
module.exports = {
async register(prm) { emailExists(prm) // emailExists is not defined  },
async emailExists(prm) { // do something } 
} 

I have a couple of questions
should I use a class that contains all the methods in the services layer
or that’s not a best practice to use a class for the services layer
or should I declare the functions and then exporting?

>Solution :

You have various choices:

• use the this keyword (doesn’t work if the require()d module is destructed):

  module.exports = {
    async register(prm) { this.emailExists(prm) },
    async emailExists(prm) { /* do something */ },
  };
  

• refer to the method as part of module.exports:

  module.exports = {
    async register(prm) { module.exports.emailExists(prm) },
    async emailExists(prm) { /* do something */ },
  };
  

• declare local functions up-front, then export them:

  async function register(prm) { emailExists(prm) }
  async function emailExists(prm) { /* do something */ }
  module.exports = { register, emailExists };
  

No, you should not use a class unless you actually need multiple different instances.