querystring参数小利器
querystring.stringify({name:‘lqc‘,course:[‘jade‘,‘node‘],from:‘‘})
//输出‘name=lqc&course=jade&course=node&from=‘
querystring.stringify({name:‘lqc‘,course:[‘jade‘,‘node‘],from:‘‘},‘,‘)
//输出‘name=lqc,course=jade,course=node,from=‘
querystring.stringify({name:‘lqc‘,course:[‘jade‘,‘node‘],from:‘‘},‘,‘,‘:‘)
//输出‘name:lqc,course:jade,course:node,from:‘
//反序列化，解析url的querystring字符串
querystring.parse(‘name=lqc&course=jade&course=node&from=‘)
//输出{ name: ‘lqc‘, course: [ ‘jade‘, ‘node‘ ], from: ‘‘ }
//转义：
querystring.escape(‘哈哈‘)
//输出‘%E5%93%88%E5%93%88‘
//反转义：
querystring.unescape(‘%E5%93%88%E5%93%88‘)
//输出‘哈哈‘
查看chrome浏览器的缓存
输入网址：chrome://net-internals/#dns
HTTP知识填坑：
状态码：status code
200
400
401
403
404
500
503
HTTP模块
HTTP事件回调
1.回调（把函数作为参数传递进去function add(callback) {console.log(callback)}function callback() {return
‘I am callback‘;}add(callback());）
function add(callback) {var value = callback(); console.log(‘Excuse me, ‘ + value)}
function callback() {return‘I am callback‘;}
add(callback);
callback.js文件：
1 /**
2 * 回调
3 * */
4 function learn(something){
5 console.log(something);
6 }
7
8 function we(callback, something) {
9 something += ‘ is cool‘;
10 callback(something);
11 }
12
13 we(learn, ‘Nodejs‘);
//命令行执行此文件
node callback
1 //传递一个匿名函数
2 we(function (something) {
3 console.log(something);
4 }, ‘JavaScript‘);
2.同步/异步
1 var c = 0;
2
3 function printIt() {
4 console.log(c);
5 }
6
7 function plus() {
8 //延迟1s
9 setTimeout(function () {
10 c += 1;
11 }, 1000);
12 }
13
14 plus();
15 printIt();//结果为0
/*************************************************************/
//异步执行
1 var c = 0;
2
3 function printIt() {
4 console.log(c);
5 }
6
7 function plus(callback) {
8 //延迟1s
9 setTimeout(function () {
10 c += 1;
11 callback();
12 }, 1000);
13 }
14
15 plus(printIt);
3.I/O
4.单线程/多线程
5.阻塞/非阻塞
6.事件
7.事件驱动
8.基于事件驱动的回调
9.事件循环
HTTP源码解读
作用域
1 ar globalVariable = ‘This is global variable‘;
2
3 function globalFunction () {
4 //局部变量
5 var localVariable = ‘This is local variable‘;
6 console.log(‘Visit global/local variable‘);
7 console.log(globalVariable);
8 console.log(localVariable);
9
10 globalVariable = ‘This is changed variable‘;
11 console.log(globalVariable);
12
13 function localFunction () {
14 var innerLocalVariable = ‘This is inner local variable‘;
15 console.log(‘Visit local function‘);
16 }
17
18 localFunction();
19 }
20
21 globalFunction();
上下文
1 //声明一个对象变量
2 var pets = {
3 words: ‘...‘,
4 name: ‘ErBao‘,
5 kind: ‘rabbit‘,
6 speak: function () {
7 console.log(this.words); // ...
8 console.log(this === pets); // true
9 }
10 };
11
12 pets.speak();
/*************************************/
1 function pets(words) {
2 this.words = words;
3
4 console.log(this.words);
5 console.log(this); //这里的this并不是pets，而是顶层的global对象
6 console.log(this === global); // true
7 }
8
9 pets(‘...‘);
this上下文对象是谁取决于函数的调用方式：1.直接调用(this表示全局对象) 2.实例化对象调用(this表示实例化的那个对象)
/*********************************/
1 function Pets(words) {
2 this.words = words;
3 this.speak = function () {
4 console.log(this.words);
5 console.log(this);
6 };
7 console.log(this);
8
9 /**
10 Pets { words: ‘ErBao‘, speak: [Function] }
11 ErBao
12 Pets { words: ‘ErBao‘, speak: [Function] }*/
13 }
14
15 //定义一个实例对象
16 var rabbit = new Pets(‘ErBao‘);
17 rabbit.speak();
/***********************************************/
call()，apply()
1 var pets = {
2 words: ‘...‘,
3 speak: function (say) {
4 console.log(say + this.words);
5 }
6 };
7
8 //pets.speak(‘Speak ‘);
9
10 var dog = {
11 words: ‘wang‘
12 };
13
14 //call()方法实现JavaScript继承，改变执行上下文
15 //父对象.父对象的方法.call(子对象, 父对象方法的参数值),父对象的方法继承给子对象
16 //pets对象转换为dog对象，同时调用pets对象的方法
17 pets.speak.call(dog, ‘Speak ‘); // Speak wang
/***********************************************/
call、apply实现继承
//定义一个构造函数
1 //定义一个构造函数
2 function Pets(words) {
3 this.words = words;
4
5 this.speak = function () {
6 console.log(this.words);
7 };
8 }
9
10 function Dog(words) {
11 Pets.call(this, words);
12 //Pets.apply(this, []);
13 }
14
15 var dog = new Dog(‘HuaHua‘);
16 dog.speak(); //HuaHua