php+ajax文章自动保存代码实例方法

var userAgent = navigator.userAgent.toLowerCase();
var is_opera  = (userAgent.indexOf('opera') != -1);
var is_saf    = ((userAgent.indexOf('applewebkit') != -1) || (navigator.vendor == 'Apple Computer, Inc.'));
var is_webtv  = (userAgent.indexOf('webtv') != -1);
var is_ie     = ((userAgent.indexOf('msie') != -1) && (!is_opera) && (!is_saf) && (!is_webtv));
var is_ie4    = ((is_ie) && (userAgent.indexOf('msie 4.') != -1));
var is_moz    = ((navigator.product == 'Gecko') && (!is_saf));
var is_kon    = (userAgent.indexOf('konqueror') != -1);
var is_ns     = ((userAgent.indexOf('compatible') == -1) && (userAgent.indexOf('mozilla') != -1) && (!is_opera) && (!is_webtv) && (!is_saf));
var is_ns4    = ((is_ns) && (parseInt(navigator.appVersion) == 4));
var is_mac    = (userAgent.indexOf('mac') != -1);
if ((is_ie & !is_ie4) || is_moz || is_saf || is_opera)
{
    var allowajax=1;
}else{
    var allowajax=0;
}
var xmlHttp = false;
function makeSendData(postData,url,functionName,httptype) {

var posturl=url;
try {
   xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
   try {
     xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
   } catch (e2) {
     xmlHttp = false;
   }
}
if (!xmlHttp && typeof XMLHttpRequest != 'undefined') {
   xmlHttp = new XMLHttpRequest();
}

if (!xmlHttp) {
        alert('Cannot send an XMLHTTP request');
        return false;
}

// 提交表单的方式
xmlHttp.open(httptype, posturl, true);

// 当表单提交完成后触发一个事件
var changefunc="xmlHttp.onreadystatechange = "+functionName;  ///////from bob
eval (changefunc);
xmlHttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
xmlHttp.send(postData);
}
function autosave_post()
{
    var title=document.getElementById('title').value;
    var content = window.frames["Editor"].window.frames["HtmlEditor"].document.getElementsByTagName("BODY")[0].innerHTML;
    var postTime=document.getElementById('postTime').value;
    if(allowajax==1)
    {
        content=postencode(content);
        title=postencode(title);
        var post="title="+title+"&content="+content+"&postTime="+postTime+"";
        var url="ajax.php?act=autosave";
        makeSendData(post,url,'autosave','POST');
    }
}
function autosave()
{
    if(xmlHttp.readyState == 4)
    {
        if(xmlHttp.status == 200)
        {
            var autoresponse=xmlHttp.responseText;
            var automessage=document.getElementById('autosavetimebox');
            if(autoresponse.indexOf("")!=-1)
            {
                automessage.innerHTML='您还没有添写信息，不用保存草稿';
                return false;
            }
            if(autoresponse.indexOf("")!=-1)
            {
                automessage.innerHTML='保存成功，您可以在发生意外的时候载入草稿';
                finddraft();
            }
        }
    }
}
function finddraft()
{
    if(allowajax==1)
    {
        var url="ajax.php?act=loaddraft";
        makeSendData(null,url,'loaddraft','POST');
    }
}
function loaddraft()
{
    var draftbox=document.getElementById('draft');
    if(xmlHttp.readyState < 4)
    {
        draftbox.innerHTML='草稿载入中...';
    }
    if(xmlHttp.readyState == 4)
    {
        if(xmlHttp.status == 200)
        {
            draftbox.innerHTML=xmlHttp.responseText;
        }
    }
}
function cleardraft()
{
    if(allowajax==1)
    {
        var url="ajax.php?act=cleardraft";
        makeSendData(null,url,'nodraft','POST');
    }
}
function nodraft()
{
    var draftbox=document.getElementById('draft');
    if(xmlHttp.readyState < 4)
    {
        draftbox.innerHTML='载入中...';
    }
    if(xmlHttp.readyState == 4)
    {
        if(xmlHttp.status == 200)
        {
            draftbox.innerHTML=xmlHttp.responseText;
        }
    }
}
//encode string
function postencode (str) {
    str=encodeURIComponent(str);
    if (is_moz) str=str.replace(/%0A/g, "%0D%0A"); //from bob
    return str;
}