node入门笔记

一、Node简介

node是一个基于v8引擎的JavaScript运行环境。

二、全局对象

setTimeout

setInterval

clearTimeout

clearInterval

console

//当前目录下的文件

console.log(__dirname);

//当前文件名

console.log(__filename);

三、模块

app.js

//模块
var obj = require('./count.js');
console.log(obj.arr);
console.log(obj.adder(3,2));
console.log('there is ' + obj.arr.length + ' fruits in the packet');

count.js

var arr = ['apple', 'banana', 'orange'];

var adder = function(a,b) {
    return `this result is ${a+b}`;
}

/* module.exports.arr = arr;
module.exports.adder = adder; */

//等价于,这里exports出了一个对象
module.exports = {
    arr: arr,
    adder: adder
}

四、事件

//事件核心库
var events = require('events');
//新增事件
var myEmitter = new events.EventEmitter();
//给事件绑定函数
myEmitter.on('someEvent', function(message) {
    console.log(message);
})
//触发事件
myEmitter.emit('someEvent', 'the event was emmited');

//导入一个工具库
var util = require('util');

var Person = function(name) {
    this.name = name
}

//继承所有Person的事件
util.inherits(Person, events.EventEmitter);

var xiaoming = new Person('xiaoming');
var lili = new Person('lili');
var lucy = new Person('lucy');

var Person = [xiaoming, lili, lucy];
//绑定事件
Person.forEach(person => {
    person.on('speak', message => {
        console.log(person.name + ' said ' + message);
    })
});
//触发事件
xiaoming.emit('speak','hi');
lili.emit('speak','hello');
lucy.emit('speak','nihao');

五、读写文件（同步、异步）

var fs = require('fs');
//同步读取文件
var readMe = fs.readFileSync('./test1/readMe.txt','utf8');
//同步写文件
fs.writeFileSync('writeMe.txt', readMe);
//异步读取文件
fs.readFile('./test1/readMe.txt','utf8', function(err,data){
    console.log(data);
});
//异步写文件
fs.writeFile('writeMe2.txt', readMe,function(err,data){
    console.log('data is copyed');
});

六、创建和删除文件

//创建文件
fs.mkdir('stuff',function(){
    fs.readFile('readMe.txt', 'utf8',function(err,data){
        fs.writeFile('./stuff/writeMe.txt',data,function(){
            console.log('copy successfully');
        })
    })
});

//删除文件
fs.unlink('readMe.txt',function(){
    console.log('this file is deleted');
});

七、流和管道

ls => 查看当前目录下的文件

ls | grep xx => 查看当前目录下是否含有xx文件

var fs = require('fs');
var myReadStream = fs.createReadStream(__dirname + '/test1/readMe.txt', 'utf8');
var myWriteStream = fs.createWriteStream(__dirname + '/test1/writeMe.txt','utf8');
var data = '';
myReadStream.on('data', function(chunk) {
    //data += chunk;
    myWriteStream.write(chunk);
})

myReadStream.on('end', function() {
    //console.log(data);
})

var fs = require('fs');
var myReadStream = fs.createReadStream(__dirname + '/test1/readMe.txt', 'utf8');
var myWriteStream = fs.createWriteStream(__dirname + '/test1/writeMe.txt','utf8');

var writeData = 'hello world';
myWriteStream.write(writeData);
myWriteStream.end();
myWriteStream.on('finish', function() {
    console.log('finished');
})

//用管道实现复制文件
myReadStream.pipe(myWriteStream);

八、web服务器

 创建一个本地的服务器：

var http = require('http');

var server = http.createServer(function(request, response) {
    response.writeHead(200, { 'Content-Type': 'text/plain'});
    //response.write('Hello from out application');
    response.end('Hello from out application');
})

server.listen(3000, '127.0.0.1');

传入纯文本：

var http = require('http');

var onRequest = function(request, response) {
    response.writeHead(200, { 'Content-Type': 'text/plain'});
    //response.write('Hello from out application');
    response.end('Hello world');
}

var server = http.createServer(onRequest);
server.listen(3000, '127.0.0.1');
console.log('Server started at ls port:3000');

传入json对象：

var http = require('http');

var onRequest = function(request, response) {
    response.writeHead(200, { 'Content-Type': 'text/json'});
    //response.write('Hello from out application');
    var myObj = {
        name: 'sasbfhad',
        job: 'coder',
        age: '21'
    };
    response.end(JSON.stringify(myObj));
}

var server = http.createServer(onRequest);
server.listen(3000, '127.0.0.1');
console.log('Server started at ls port:3000');

传html：

var http = require('http');
var fs = require('fs');
var onRequest = function(request, response) {
    response.writeHead(200, { 'Content-Type': 'text/html'});
    //response.write('Hello from out application');
    var myReadStream = fs.createReadStream(__dirname + '/shiyan.html', 'utf8');
    myReadStream.pipe(response);
}

var server = http.createServer(onRequest);
server.listen(3000, '127.0.0.1');
console.log('Server started at ls port:3000');

封装：

app.js

var server = require('./server');

server.startServer();

server.js

var http = require('http');
var fs = require('fs');
function startServer() {
    var onRequest = function(request, response) {
        response.writeHead(200, { 'Content-Type': 'text/plain'});
        //response.write('Hello from out application');
        var myReadStream = fs.createReadStream(__dirname + '/shiyan.html', 'utf8');
        myReadStream.pipe(response);
    }    

    var server = http.createServer(onRequest);
    server.listen(3000, '127.0.0.1');    
    console.log('Server started at ls port:3000');
}

module.exports.startServer = startServer;