Aya-Sato / m4-5-node--async-await

4-5 - Node JS - Async / Await

Setup

• yarn install

You will not need to spin up a server in this workshop. You can "run" the files individually in the terminal by doing node <PATH_TO_FILE> for most of the exercises.

Exercise 0

In the example from last workshop we had a Promise that compared a number to the number 10.

// The Promise
const compareToTen = (num) => {
  return new Promise((resolve, reject) => {
    num > 10
      ? resolve(num + " is greater than 10, success!")
      : reject(num + " is less than 10, error!");
  });
};

// Calling the Promise
compareToTen(15)
  .then((result) => console.log(result))
  .catch((error) => console.log(error));

If we convert the Promise call, to an async function that includes a try/catch (for better error handling), we end up with something like this:

const handleCompareToTen = async (num) => {
  try {
    const result = await compareToTen(num);
    console.log(result);
  } catch {
    console.log(err);
  }
};

// Calling the function (that uses the Promise)
handleCompareToTen(15);
handleCompareToTen(8);

Using async/await in this case requires a little more setup as we create a function that uses the Promise, but calling the code becomes much simpler as there is no need to chain a bunch of thens everytime we want to use the Promise.

Exercise 1

Rewrite the text transformation exercise from the last workshop to use async/await.

Exercise 2 - getIssPosition

Async/Await becomes much more useful when dealing with APIs, and modules that wrap Promises.

Fill in the blanks of a rewritten version of the getIssPosition code from last workshop.

Exercise 3

1. Write a function called doublesLater that returns a new Promise that doubles a number after 2 seconds.
2. Here is a promise called handleSum uses the doublesLater Promise. It takes a num, doubles it 3 times (with the doublesLater Promise), and returns the sum of the three successive doubles. As you can see, it is quite the hellish situation. it is also a convoluted and totally fabricated situation...

const handleSum = (num) => {
  let theSum = 0;
  return new Promise((resolve) => {
    doublesLater(num).then((a) => {
      theSum += a;
      doublesLater(a).then((b) => {
        theSum += b;
        doublesLater(b).then((c) => {
          theSum += c;
          resolve(theSum);
        });
      });
    });
  });
};

3. Rewrite handleSum with async/await.

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Exercise 4 - Just Jokes!

Exercise 4.1 - getDadJoke

1. Head over to https://icanhazdadjoke.com/api. Read the documentation...
2. Write a Promise that called getDadJoke that will return a random joke from this API. Return only the actual joke as a string.
3. The request-promise module accepts a uri but can also accept an object with various parameters. You will want to set the headers to "Accept": "application/json"
4. console.log the result to read the joke.

READ the request-promise NPM page for more information.

Exercise 4.2 - getTronaldDumpQuote

1. Head over to https://docs.tronalddump.io/. Read the documentation...
2. Write a Promise that will return a random Tronald Dump quote. I had a hard time actually finding the api endpoint... Here it is: https://api.tronalddump.io
3. Examine the response to get the right data to return.
4. Return only the quote as a string.

Exercise 4.3 - getGeekJoke

1. Head over to https://github.com/sameerkumar18/geek-joke-api. Read the documentation...
2. Write a Promise that will return a random joke.

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🟡 - Minimally complete workshop (75%) - 🟡

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Exercise 5 - A Backend Joke Service

We are going to create a server that will respond with a joke based on the endpoint that the user calls.

1. Export the joke functions you wrote in Exercise 4.
   • Go back to each function in exercise 4 and add in a line at the bottom of the file that exports the function.

module.exports = { myFunction };

2. In server.js create the following endpoint:

/joke/:type

3. Require all of the joke functions in the provided handlers.js file.
4. This file should also contain a function called handleJoke that returns a joke of the type requested (dad, tronald or geek).
5. Don't forget to do yarn dev to run the server.

🟢 - Complete workshop (100%) - 🟢

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Exercise 6 - The Frontend

Add a React Frontend to render the jokes to the browser.