Express develop guide

1. handling forms in express

<form method="POST" action="/submit-form">
  <input type="text" name="username" />
  <input type="submit" />
</form>

When the user press the submit button , the browser will automatically make a POST request to the /submit-form URL on the same origin of the page, sending the data it contains, encoded as application/x-www-form-urlencoded . In this case, the form data contains the usename input field value.

To extract it, you will use the express.urlencoded() middleware, provided by Express:

const express = require('express')
const app = express()
app.use(express.urlencoded())

Now you need to create a POST endpoint on the /submit-form route, and any data will be available on Request.body :

app.post('/submit-form', (req, res) => {
    const username = req.body.username;
    res.end()
})

Don’t forget to validate the data before using it, using express-validator .

1. Node, the difference between development and production

You can have different configurations for production and development environments.

Node assumes it’s always running in a development environment. You can signal Node.js that you are running in production by setting the NODE_ENV=production environment variable.

This is usually done by executing the common

export NODE_ENV=production

Setting the environment to production generally ensures that

• logging is kept to a minimum, essential level

• more caching levels take place to optimize performance.

Express provides configurations hooks specific to the environment, which are automatically called based on the NODE_ENV variable value:

app.configure('development', () => {
    // ...
})
app.configure('production', () => {
    // ...
})
app.configure('production', 'staging', () => {
    // ...
})

For example you can use this to set different error handlers for different mode:

app.configure('development', () => {
    app.use(express.errorHandler({ dumpExceptions: true, showStack: true }));
});
app.configure('production', () =>{
    app.use(express.errorHandler());
});

1. Manage cookies with express

Use the Response.cookie() method to manipulate your cookies.

Examples:

res.cookie('username', 'Flavio')

This method accepts a third parameter which contains various options:

res.cookie('username', 'Flavio', {
    domain: '.yuque.com',
    path: '/administrator',
    secure: true
});
res.cookie('username', 'Flavio', {
    expires: new Date(Date.now() + 900000),
    httpOnly: true,
});

The most useful parameters you can set are:

A cookie can be cleared with

res.clearCookie('username')