First Class Functions #
// Number -> Number
function add1(xx) {
return xx + 1;
}
// (Number -> Number), Number -> Number
function doTwice(op, xx) {
return op(op(xx));
}
// (Number -> Number) -> (Number -> Number)
function twice(op) {
function inner(xx) {
return op(op(xx));
}
return inner;
}
// (Number -> Number) -> (Number -> Number)
function twice(op) {
return (xx) => op(op(xx));
}
Web App #
$ mkdir edemo; cd edemo
$ pnpm install express
const express = require('express')
const app = express()
const port = 3000
app.get('/', (req, res) => {
res.set('Content-Type', 'text/html')
res.send(`
<!doctype html>
<form action="/hello">
<p><input type="text" name="name"></p>
<p><button>Submit</button></p>
</form>
`)
})
app.listen(port, () => {
console.log(`Example app listening on port ${port}`)
})
$ node app.js
Then visit localhost:3000 in browser
More
Post Requests #
$ npm install body-parser
const express = require('express');
const app = express();
const port = 3000;
const bodyParser = require('body-parser');
function rootPath(req, res) {
res.set('Content-Type', 'text/html');
res.send(`
<!doctype html>
<form action="/hello" method="post">
<p><input type="text" name="name"></p>
<p><button>Submit</button></p>
</form>
`);
}
app.get('/', rootPath);
let parser = bodyParser.urlencoded({ extended: false });
function helloPath(req, res) {
let name = req.body.name;
res.set('Content-Type', 'text/html');
res.send(`
<!doctype html>
<p>Hello, ${name}</p>
`);
}
app.post('/hello', parser, helloPath);
function startup() {
console.log(`Example app listening on port ${port}`)
}
app.listen(port, startup);
NextJS #
- Do a NextJS demo, without state or anything.
