var jsonText = JSON.stringify(book,null,4);
//结果：
{
    "title": "title",
    "author": [
        "Nicholas C. Zakas"
    ],
    "edition": 3,
    "year": 2011
}

function createXHR(){
    if(typeof XMLHttpRequest != "undefined"){
        return new XMLHttpRequest;
    }else if(typeof ActiveXObject != "undefined"){
        if(typeof arguments.callee.activeXString != "string"){
            var versions = ["MSXML2.XMLHttp.6.0","MSXML2.XMLHttp.3.0","MSXML2.XMLHttp"],i,len;
            for(i=0,len=versions.length;i < len;i++){
                try{
                    new ActiveXObject(versions[i]);
                    arguments.callee.activeXString = versions[i];
                    break;
                }catch(ex){
                    //跳过
                }
            }
        }
        return new ActiveXObject(arguments.callee.activeXString);
    }else{
        throw new Error("No XHR Object available");
    }
}
//使用示例
var xhr = createXHR();

function submitData(){
    var xhr = createXHR();
    xhr.onreadystatechange = function(){
        if(xhr.readyState == 4){
            if((xhr.status >= 200 && xhr.status < 300) || xhr.status == 304){
                alert(xhr.resopnseText);
            }else{
                alert("Request was unsuccessful: "+xhr.status);
            }
        }
    };

    xhr.open("post","postExample.php",true);
    xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
    var form = document.getElementById("user-info");
    xhr.send(serialize(form));
}

<?php
    header("Content-Type:text/plain");
    echo <<<EOF
    Name:{$_POST[‘user-name‘]}
    Email:{$_POST[‘user-email‘]}
    EOF;
?>

var data = new FormData();
data.append("name","Nicholas");          //接收两个参数：键，值

var data = new FormData(document.forms[0]);     //直接使用表单元素

var form = document.getElementById("user-info");
xhr.send(new FormData(form));

var socket = new WebSocket("ws://www.example.com/server.php");

socket.close();

socket.send("hello world");          //任意字符串

var socket = new WebSocket("ws://www.example.com/server.php");
var CookieUtil = {
    get:function(name){
        var cookieName = encodeURIComponent(name) + "=" ,
            cookieStart = document.cookie.indexOf(cookieName),
            cookieValue = null;

        if(cookieStart > -1){
            var cookieEnd = document.cookie.indexOf(";",cookieStart);
            if(cookieEnd == -1){
                cookieEnd = document.cookie.length;
            }
            cookieValue = decodeURIComponent(document.cookie.substring(cookieStart+cookieName.length,cookieEnd));
        }

        return cookieValue;
    },
    set:function(name,value,expires,path,domain,secure){
        var cookieText = encodeURIComponent(name) + "=" + encodeURIComponent(value);

        if(expires instanceof Date){
            cookieText += "; expires=" + expires.toGMTString();
        }
        if(path){
            cookieText += "; path=" + path;
        }
        if(domain){
            cookieText =+ "; domain=" + domain;
        }
        if(secure){
            cookieText += "; secure=" + secure;
        }
        document.cookie = cookieText;
    },
    unset:function(name,path,domain,secure){
        this.set(name,"",new Date(0),path,domain,secure);
    }
};

//设置cookie
CookieUtil.set("name","Nicholas");
CookieUtil.set("book","Professional JavaScript");

//读取
alert(CookieUtil.get("name"));  //"Nicholas"
alert(CookieUtil.get("book"));  //Professional JavaScript

//删除
CookieUtil.unset("name");
CookieUtil.unset("book");

//设置cookie，包括它的路径、域、失效日期
CookieUtil.set("name","Nicholas","/books/projs","www.wrox.com",new Date("January 1,2010"));

//删除刚设置的cookie
CookieUtil.unset("name","/books/projs","www.wrox.com");

//设置安全cookie
CookieUtil.set("name","Nicholas",null,null,null,true);