api.md

For today's lesson, we're going to learn how to build a simple node js API!

API's are the backbone of building any app. It's how you can connect to a database, how you can accept payments, and how you can serve data to any application

A few prerequisites:

• Basic knowledge of terminal commands
• node installed
• yarn or npm installed

---

Clone the starter repo

git clone git@github.com:milesalex/node-template.git api

Enter the folder and install the dependencies

cd app/
yarn install

Go to app.js and take a look at whats inside

import express from 'express'

const app = express()

app.get('/', (req, res) => {
  const response = { message: 'Hello from our api!' }
  res.json(response)
})

module.exports = app

Let's go through what's here. We import express, and then create an instance of our app by saving the express instance to a variable called app.

In express, it's very easy to create what's called "routes":

app.get('/', (req, res) => {
  const response = { message: 'Hello from our api!' }
  res.json(response)
})

When running an express server on your local computer, it will create a url. For example http://localhost:3000. The http://localhost part means "my local computer" and the 3000 means the port that the app is running on.

With the above code, this will create a webpage at the root url or '/'. Inside the code block, we store a json object as response and then we pass it to res.json().

The only thing thats important th know here is this is how you send JSON data to a website!

The final code in `app.js should look like this

import express from 'express'

const app = express()

app.get('/', (req, res) => {
  const response = { message: 'Hello from our api!' }
  res.json(response)
})

module.exports = app

Now, go back to the terminal and run

yarn run dev

And then you should see

DONE  Compiled successfully in 30ms

Example app listening on port http://localhost:5678!

Go to http://localhost:5678 and you should see a json response like this!!!

{
  "message": "Hello from our api!"
}

Yayy!! You just built an API! This is a core build block of building apps. Play around, see what you can do!