Server-Side Scripting/Iteration/Node.js (Express)
routes/lesson4.js
edit// Demonstrates conditions, while loops and for loops using
// Celsius and Fahrenheit temperature conversion tables.
//
// References:
// https://www.mathsisfun.com/temperature-conversion.html
// https://en.wikibooks.org/wiki/JavaScript
// https://stackabuse.com/get-query-strings-and-parameters-in-express-js/
// https://flaviocopes.com/express-forms/
// https://expressjs.com/en/guide/routing.html
const express = require('express')
const fs = require("fs");
const handlebars = require('handlebars');
const router = express.Router()
router.get("/", function (request, response) {
let source = fs.readFileSync("./templates/lesson4.html");
let template = handlebars.compile(source.toString());
let data = {
table: ""
}
result = template(data);
response.send(result);
});
router.post("/", function (request, response) {
let start = Number(request.body.start);
let stop = Number(request.body.stop);
let increment = Number(request.body.increment);
let submit = request.body.submit;
let result = "";
if (submit == "Celsius") {
result = processCelsius(start, stop, increment);
}
else if (submit == "Fahrenheit") {
result = processFahrenheit(start, stop, increment);
}
else {
result = "Unexpected submit value: " + submit;
}
let source = fs.readFileSync("./templates/lesson4.html");
let template = handlebars.compile(source.toString());
let data = {
table: result
}
result = template(data);
response.send(result);
});
function processCelsius(start, stop, increment) {
let result = "<table><tr><th>Celsius</th><th>Fahrenheit</th></tr>";
let celsius = start;
while (celsius <= stop) {
let fahrenheit = celsius * 9 / 5 + 32;
result += "<tr><td>" + celsius + "</td>";
result += "<td>" + fahrenheit.toFixed(1) + "</td></tr>";
celsius += increment;
}
result += "</table>";
return result;
}
function processFahrenheit(start, stop, increment) {
let result = "<table><tr><th>Fahrenheit</th><th>Celsius</th></tr>";
for (let fahrenheit = start; fahrenheit <= stop; fahrenheit += increment) {
let celsius = (fahrenheit - 32) * 5 / 9;
result += "<tr><td>" + fahrenheit + "</td>";
result += "<td>" + celsius.toFixed(1) + "</td></tr>";
}
result += "</table>";
return result;
}
module.exports = router;
templates/lesson4.html
edit<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Lesson 4</title>
<link rel="stylesheet" href="styles.css">
<style>
p {
min-height: 1em;
}
</style>
</head>
<body>
<h1>Temperature Conversion</h1>
<form method="POST">
<p><label for="start">Start:</label>
<input type="text" id="start" name="start" value="0">
</p>
<p><label for="stop">Stop:</label>
<input type="text" id="stop" name="stop" value="100">
</p>
<p><label for="increment:">Increment</label>
<input type="text" id="increment" name="increment" value="10">
</p>
<p><input type="submit" name="submit" value="Celsius">
<input type="submit" name="submit" value="Fahrenheit">
</p>
</form>
{{{table}}}
</body>
</html>
Try It
editSee Server-Side Scripting/Routes and Templates/Node.js (Express) to create a test environment.