NodeJS基础篇

以下内容来非常棒的讲解：Node JS Tutorial for Beginners，我已经爱上 The Net Ninja 的教程了！（PS：多图预警）

Node.js ACTUALLY is... Why is Node.js so Popular? What We'll Learn... JavaScript Engine Machine Code So... Node.js with V8

Basic demos

var fs = require('fs');

/**
 * 创建目录
 */
// 同步创建目录
// fs.mkdirSync('stuff');

// 异步创建目录
fs.mkdir('stuff', function() {
        // 异步读取文件
    fs.readFile('readMe.txt', 'utf8', function(err, data) {
                // 异步写文件
        fs.writeFile('./stuff/writeMe.txt', data);
    });
});

/**
 * 删除文件及目录
 */
// 删除已经存在的文件
fs.unlink('./stuff/writeMe.txt', function() {
    // 异步删除目录
    fs.rmdir('stuff');
    // 同步删除目录
    // fs.rmdirSync('stuff');
});

Response Headers

var http = require('http');

var server = http.createServer(function(req, res) {
    console.log('request was made: ' + req.url);
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('Hey ninjas');
});

server.listen(3000, '127.0.0.1');

Buffers So... Streams Streams in Node.js Streams

var http = require('http');
var fs = require('fs');

var myReadStream = fs.createReadStream(__dirname + '/readMe.txt', 'utf8');
var myWriteStream = fs.createWriteStream(__dirname + '/writeMe.txt');

myReadStream.on('data', function(chunk) {
    console.log('new chunk received');
    myWriteStream.write(chunk);
});

Pipes

var http = require('http');
var fs = require('fs');

var myReadStream = fs.createReadStream(__dirname + '/readMe.txt', 'utf8');
var myWriteStream = fs.createWriteStream(__dirname + '/writeMe.txt');

myReadStream.pipe(myWriteStream);

Pipes: don't have to manually listen for data events and we don't have to manually write to a write stream, it takes care all of that for us.

we can only use pipe method on Readable streams because we're piping from a Readable stream to a Writable stream. We can't pipe from a writable stream to a readable stream because we can't read from that.

var http = require('http');
var fs = require('fs');

var server = http.createServer(function(req, res) {
    console.log('request was made: ' + req.url);
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    var myReadStream = fs.createReadStream(__dirname + '/readMe.txt', 'utf8');
    myReadStream.pipe(res);  // the response object is a writable stream
});

server.listen(3000, '127.0.0.1');

Serving HTML Pages

var http = require('http');
var fs = require('fs');

var server = http.createServer(function(req, res) {
    console.log('request was made: ' + req.url);
    res.writeHead(200, { 'Content-Type': 'text/html' });  // modify Content-Type
    var myReadStream = fs.createReadStream(__dirname + '/index.html', 'utf8');
    myReadStream.pipe(res);
});

server.listen(3000, '127.0.0.1');

Serving JSON Data

var http = require('http');
var fs = require('fs');

var server = http.createServer(function(req, res) {
    console.log('request was made: ' + req.url);
    res.writeHead(200, { 'Content-Type': 'application/json' });  // modify Content-Type
    var myObj = {
        name: 'Ryu',
        job: 'Ninja',
        age: 29
    };
    res.end(JSON.stringify(myObj)); // expects a string or a buffer
});

server.listen(3000, '127.0.0.1');

res.end() expects a string or a buffer

Basic Routing

var http = require('http');
var fs = require('fs');

var server = http.createServer(function(req, res) {
    console.log('request was made: ' + req.url);
    if (req.url === '/home' || req.url === '/') {
        res.writeHead(200, { 'Content-Type': 'text/html' });
        fs.createReadStream(__dirname + '/index.html').pipe(res);
    } else if (req.url === '/contact') {
        res.writeHead(200, { 'Content-Type': 'text/html' });
        fs.createReadStream(__dirname + '/contact.html').pipe(res);
    } else if (req.url === '/api/ninjas') {
        var ninjas = [{ name: 'ryu', age: 29 }, { name: 'yoshi', age: 32 }];
        res.writeHead(200, { 'Content-Type': 'application/json' });
        res.end(JSON.stringify(ninjas));
    } else {
        res.writeHead(404, { 'Content-Type': 'text/html' });
        fs.createReadStream(__dirname + '/404.html').pipe(res);
    }
});

server.listen(3000, '127.0.0.1');

Express

1. basic

var express = require('express');
var app = express();

app.get('/', function(req, res) {
    res.send('this is the homepage');
});

app.get('/contact', function(req, res) {
    res.send('this is the contact page');
});

app.get('/profile/:id', function(req, res) {
    res.send('You requested to see a profile with the id of ' + req.params.id);
})

app.listen(3000);

2. Templage Engines

var express = require('express');

var app = express();

app.set('view engine', 'ejs');

app.get('/', function(req, res) {
    res.sendFile('index');
});

app.get('/contact', function(req, res) {
    res.sendFile('contact');
});

app.get('/profile/:name', function(req, res) {
    var data = { age: 20, job: 'ninja', hobbies: ['eating', 'fighting', 'fishing'] };
    res.render('profile', { person: req.params.name, data });   // render profile view with person
})

app.listen(3000);

// profile.ejs
<!DOCTYPE html>
<html>
<head>
</head>
<body>
    <% include partials/nav.ejs %>
    <h1>Welcome to the profile of <%= person %></h1>
    <p>Age: <%= data.age %></p>
    <p>Job: <%= data.job %></p>
    <h2>Hobbies</h2>
    <ul>
        <% data.hobbies.forEach(function(item)){ %>
            <li><%= item %></li>
        <% }); %>
    </ul>
</body>
</html>

3. Static Files

app.use('/assets', express.static('assets'));

4. Query Strings

app.get('/contact', function(req, res) {
    res.render('contact', { qs: req.query });
});

5. Handling Post Requests

var bodyParser = require('body-parser');

// create application/x-www-form-urlencoded parser
var urlencodedParser = bodyParser.urlencoded({ extended: false });

app.post('/contact', urlencodedParser, function(req, res) {
    console.log(req.body);  // { who: 'ryu', department: 'marketing', email: 'ninja@ninja.com' }
    res.render('contact-success', { data: req.body });
});