{ JavaScript } npm Express & ejs - Jaydon Learning Blog

Frameworks

Express framework

Express provides a method that specifies a function called for a specific HTTP verb (GET, POST, SET, etc.).
Specifies the URL pattern (“Route”) and the “View” engine to be used, the template file location, and how to specify the template to be used to render the response.

https://www.npmjs.com/package/express

EJS framework

EJS is an module for Embedded JavaScript template, a simple template language that can create ‘HTML markups’ for JavaScript.
(If you’re a java developer, you can say you play the same role as a familiar ‘JSP’)
Logic and data necessary in-between HTML may be added using a tag in the form of <%…%>.
In particular, it is best to send server data into html directly through the for-loop or if statement.

https://www.npmjs.com/package/ejs

Simple JS Source code (BMI Calculator)

// Import modules
const express = require("express");

const app = express();
const port = 3000;

app.use(express.static("public"));
app.use(express.urlencoded({ extended: true }));

// Import npm ejs(Embedded JavaScript templating)
// which allows you to create html markup
app.engine("html", require("ejs").renderFile);
// Syntax : views, __dirname + "/" + <folderName>
app.set("views", __dirname + "/" + "webpage");

// Render basic html file
app.get("/", function (req, res) {
  res.render("bmi.html");
});

// Get request and respond rending a new page with html values
app.post("/", function (req, res) {
  let age = req.body.age;
  let weight = req.body.weight;
  let height = req.body.height;

  // TO TEST
  // console.log(age + " " + weight + " " + height);

  // Calculate BMI
  let bmi = (weight / [height * height]) * 10000;

  // One decimal point
  let result = bmi.toFixed(1);

  // Render new page with html markups
  res.render("./result.html", {
    age: age,
    weight: weight,
    height: height,
    result: result,
  });
});

app.listen(port, function () {
  console.log("Listening port " + port);
});