Example 1: express hello world
//to run : node filename.js
const express = require('express')
const app = express()
const port = 3000
app.get('/', (req, res) => res.send('Hello World!'))
app.listen(port, () => console.log(`Example app listening at http://localhost:${port}`))
//visit localhost:3000
// assuming you have done 1) npm init 2) npm install express
Example 2: node js express url parameters
// http://localhost:8080/api/1
app.get('/api/:version', function(req, res) {
res.send(req.params.version);
});
Example 3: app.get
const express = require('express');
const app = express();
const { getElementById, getIndexById, updateElement,
seedElements, createElement } = require('./utils');
const PORT = process.env.PORT || 4001;
// Use static server to serve the Express Yourself Website
app.use(express.static('public'));
const expressions = [];
seedElements(expressions, 'expressions');
const animals = [];
seedElements(animals, 'animals');
// Get all expressions
app.get('/expressions', (req, res, next) => {
res.send(expressions);
});
// Get a single expression
app.get('/expressions/:id', (req, res, next) => {
const foundExpression = getElementById(req.params.id, expressions);
if (foundExpression) {
res.send(foundExpression);
} else {
res.status(404).send();
}
});
// Update an expression
app.put('/expressions/:id', (req, res, next) => {
const expressionIndex = getIndexById(req.params.id, expressions);
if (expressionIndex !== -1) {
updateElement(req.params.id, req.query, expressions);
res.send(expressions[expressionIndex]);
} else {
res.status(404).send();
}
});
// Create an expression
app.post('/expressions', (req, res, next) => {
const receivedExpression = createElement('expressions', req.query);
if (receivedExpression) {
expressions.push(receivedExpression);
res.status(201).send(receivedExpression);
} else {
res.status(400).send();
}
});
// Delete an expression
app.delete('/expressions/:id', (req, res, next) => {
const expressionIndex = getIndexById(req.params.id, expressions);
if (expressionIndex !== -1) {
expressions.splice(expressionIndex, 1);
res.status(204).send();
} else {
res.status(404).send();
}
});
// Get all animals
app.get('/animals', (req, res, next) => {
res.send(animals);
});
// Get a single animal
app.get('/animals/:id', (req, res, next) => {
const animal = getElementById(req.params.id, animals);
if (animal) {
res.send(animal);
} else {
res.status(404).send();
}
});
// Create an animal
app.post('/animals', (req, res, next) => {
const receivedAnimal = createElement('animals', req.query);
if (receivedAnimal) {
animals.push(receivedAnimal);
res.status(201).send(receivedAnimal);
} else {
res.status(400).send();
}
});
// Update an animal
app.put('/animals/:id', (req, res, next) => {
const animalIndex = getIndexById(req.params.id, animals);
if (animalIndex !== -1) {
updateElement(req.params.id, req.query, animals);
res.send(animals[animalIndex]);
} else {
res.status(404).send();
}
});
// Delete a single animal
app.delete('/animals/:id', (req, res, next) => {
const animalIndex = getIndexById(req.params.id, animals);
if (animalIndex !== -1) {
animals.splice(animalIndex, 1);
res.status(204).send();
} else {
res.status(404).send();
}
});
app.listen(PORT, () => {
console.log(`Server is listening on ${PORT}`);
});
Example 4: express route parameters
app.get('/users/:userId/books/:bookId', function (req, res) {
res.send(req.params)
})
Example 5: express mounting router
var express = require('express')
var router = express.Router()
// middleware that is specific to this router
router.use(function timeLog (req, res, next) {
console.log('Time: ', Date.now())
next()
})
// define the home page route
router.get('/', function (req, res) {
res.send('Birds home page')
})
// define the about route
router.get('/about', function (req, res) {
res.send('About birds')
})
module.exports = router