demoing using await with a promise function

use await with promise.js

const fetch = require('node-fetch'); // fetch polyfill in node.js; not required in front end situation

// returns an promise, so it can be used by await
async function getTodo(id) {
  return new Promise((resolve, reject) => {
    fetch('https://jsonplaceholder.typicode.com/todos/' + id)
      .then(response => response.json())
      .then(json => {
        // success
        // return data through resolve
        resolve(json);
      })
      .catch(() => {
        // error 
        // caller can catch the error in try .. catch .. block
        reject();
      })
  });
}

// call this function as a promise, or use await in another async function
async function getTodos(ids) {
  let todos = [];
  for (let i = 0; i < ids.length; i++) {
    let id = ids[i];
    let todoObj = await getTodo(id);
    todos.push(todoObj);
  }

  return todos;
}

// use getTodos in another async function
// such as inside your express route handler
async function run() {
  const todoIds = ["1", "2", "3"];
  let todos = await getTodos(todoIds);
  return todos;
}

// test

run().then((todos) => {
  console.log(todos);
})