index.js

const express = require("express");
const bodyParser = require("body-parser");
const request = require("request");
const app = express();

const apiKey = "2f9db009877a47c5c26e1cdb438db537";

app.use(express.static("public"));
app.use(bodyParser.urlencoded({ extended: true }));
app.set("view engine", "ejs");

app.get("/", function(req, res) {
	res.render("index", { weather: null, error: null });
});

app.post("/", function(req, res) {
	let city = req.body.city;
	let url = `http://api.openweathermap.org/data/2.5/weather?q=${city}&units=metric&appid=${apiKey}`;

	request(url, function(err, response, body) {
		if (err) {
			res.render("index", { weather: null, error: "Error, please try again" });
		} else {
			let weather = JSON.parse(body);
			if (weather.main == undefined) {
				res.render("index", {
					weather: null,
					error: "Error, please try again"
				});
			} else {
				let weatherText = `It's ${weather.main.temp} degrees in ${weather.name}!`;
				res.render("index", { weather: weatherText, error: null });
			}
		}
	});
});

app.listen(3000, function() {
	console.log("Example app listening on port 3000!");
});