Set up localhost server

1. npm init
2. npm install express
3. create a index.html and index.js
4. node index.js
5. http://localhost:5000

//index.js
const express = require('express');
const app = express();
const port = 5000;

app.get('/', (req, res) => {
    res.sendFile('index.html', {root: __dirname});
});

app.listen(port, () => {
    console.log(`Now listening on port ${port}`);
});

Create a post api using express

const express = require('express');
const app = express();

//middleware to parse incoming request with json payload
app.use(express.json());

//middleware to parse incoming request with url encoded payload
app.use(express.urlencoded({ extended: true }));

const port = 5000;

app.get('/', (req, res) => {
    res.sendFile('index.html', { root: __dirname });
});

app.listen(port, () => {
    console.log(`Now listening on port ${port}`);
});

app.post('/api/create_transaction', (req, res) => {
    const body = req.body;
    console.log("body:", body);
    res.status(201).json([]);
});