How to create Promise

I've been using Promise without knowing how it is built. This is a note for me about Promise creation. I'm using this block of code with the archiving-app project.

In this example, I'm skipping to bring path module but it should always be there whenever you use the file system module.

const fs = require("fs");

// creating Promise
const read = () => {
  return new Promise((resolve, reject) => {
    fs.readFile("./package.json", (error, data) => {
      return error ? reject(error) : resolve(data.toString());
    });
  });
};

// using Promise
read()
  .then(data => {
    console.log(data);
  })
  .catch(error => {
    console.error(error);
  });

// creating Promise.all
const readAll = () => {
  const promises = [read(), read(), read()];
  return Promise.all(promises);
};

// using Promise.all
readAll()
  .then(data => {
    console.log(data);
  })
  .catch(error => {
    console.error(error);
  });