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一、xml httprequest和xml dom基礎

這兩個是web 開發的常用東西，就不說了，先看看使用：

var req; function postxml(xmldoc) {        if (window.xmlhttprequest) req = new xmlhttprequest();        else if (window.activexobject) req = new activexobject("microsoft.xmlhttp");        else return; // fall on our sword        req.open(method, serveruri);        req.setrequestheader('content-type', 'text/xml');        req.onreadystatechange = xmlposted;        req.send(xmldoc); } function xmlposted() {        if (req.readystate != 4) return;        if (req.status == 200) {               var result = req.responsexml;        } else {               // fall on our sword        } }

二、javascript腳本錯誤處理基礎

請教大家一個問題？如何處理腳本錯誤的？又如何去捕捉腳本錯誤的？有沒有遇到過客戶打電話抱怨系統不能運行，而你判斷可能是客戶端問題后就不知道如何處理的情況？

最新的瀏覽器都支持try/catch方式捕捉javascript異常，還有一個onerror事件來處理異常。

<script language="javascript"> riskybusiness(); window.onerror = handleerror(); // safety net to trap all errors function riskybusiness() {        try {               riskyoperation1();               riskyoperation2();        } catch (e) {               // e is an object of type error with               // at least two properties: name and message               alert(e.message);        } finally {               // clean up our mess        } } function handleerror() {        alert("handleerror()");        // alert the user that this page may not respond properly        return true; // this will stop the default message } </script>

三、將客戶端錯誤寫入服務器端的日志文件

首先，客戶端建立一個單例模式的對象logger

// singleton class constructor

function logger() {

       // fields

       this.req;

       // methods

       this.errortoxml = errortoxml;

       this.log = log;

}

其次，我們要把javascript錯誤序列化到xml對象中。默認情況下，error對象只有兩個屬性：name和message。我們需要再建立一個屬性：location。

// map an error to an xml document

function errortoxml(err) {

       var xml = '<?xml version="1.0"?>\n' +

              '<error>\n' +

              '<name>' + err.name + '</name>\n' +

              '<message>'  + err.message + '</message>\n';

       if (err.location) xml += '<location>' + err.location +

              '</location>';

       xml += '</error>';

       return xml;

}

接下來是利用xmlhttp請求將錯誤信息寫入到日志中，原文作者利用cgi寫入，這里，可以根據具體的應用情況選擇大家自己的處理方式：

// log method of logger class

function log(err) {

       // feature sniff

       if (window.xmlhttprequest) this.req = new xmlhttprequest();

       else if (window.activexobject) this.req =

              new activexobject("microsoft.xmlhttp");

       else return; // throw up our hands in despair

       // set the method and uri

       this.req.open("post", "/cgi-bin/ajaxlogger.cgi");

       // set the request headers. referer will be the top-level

       // uri which may differ from the location of the error if

       // it occurs in an included .js file

       this.req.setrequestheader('referer', location.href);

       this.req.setrequestheader('content-type', 'text/xml');

       // function to be called when the request is complete

       this.req.onreadystatechange = errorlogged;

       this.req.send(this.errortoxml(err));

       // if the request doesn't complete in 10 seconds,

       // something is up

       this.timeout = window.settimeout("abortlog();", 10000);

}

然后，我們要實例化這個類：

// should only be one instance of the logger

var logger = new logger();

最后的兩個方法用來做“家務管理”的。

// we tried, but if there is a connection error, it is hopeless

function abortlog() {

       logger.req.abort();

       alert("attempt to log the error timed out.");

}

// called when the state of the request changes

function errorlogged() {

       if (logger.req.readystate != 4) return;

       window.cleartimeout(logger.timeout);

       // request completed

       if (logger.req.status >= 400)

              alert('attempt to log the error failed.');

}

好了，把前面講述的幾個方法封裝到一個公用腳本logger.js中去吧，然后你就可以enjoy了。

在自己開發的腳本中引入這個js并使用如下：

【stone評】有問題，有興趣者可調整。

<script type="text/javascript" src="logger.js"></script>

<script type="text/javascript">

function traperror(msg, uri, ln) {

       // wrap our unknown error condition in an object

       var error = new error(msg);

       error.location = uri + ', line: ' + ln; // add custom property

       logger.log(error);

       warnuser();

       return true; // stop the yellow triangle

}

window.onerror = traperror;

function foo() {

       try {

              riskyoperation();

      } catch (err) {

              // add custom property

              err.location = location.href + ', function: foo()';

              logger.log(err);

              warnuser();

       }

}

function warnuser() {

       alert("an error has occurred while processing this page."+

              "our engineers have been alerted!");

       // drastic action

       location.href = '/path/to/error/page.html';

}

</script>

最后是在服務器端利用cgi寫入日志，代碼如下，喜歡用別的方式的程序員可以選擇利用你們擅長的語言來將xml日志信息寫入服務器端文件。

use cgi;

use cgi::carp qw(set_progname);

use xml::simple;

my $request = cgi->new();

my $method = $request->request_method();

# method must be post

if ($method eq 'post') {

       eval {

              my $content_type = $request->content_type();

              if ($content_type eq 'text/xml') {

                     print $request->header(-status =>

                         '415 unsupported media type', -type => 'text/xml');

                     croak "invalid content type: $content_type\n";

              }

              # when method is post and the content type is neither

              # uri encoded nor multipart form, the entire post

              # is stuffed into one param: postdata

              my $error_xml = $request->param('postdata');

              my $ref = xml::simple::xmlin($error_xml);

              my ($name, $msg, $location) =

                     ($ref->{'name'}, $ref->{'message'}, '');

              $location = $ref->{'location'} if (defined($ref->{'location'}));

              # this will change the name of the carper in the log

              set_progname('client-side error');

              my $remote_host = $request->remote_host();

              carp "name: [$name], msg: [$msg], location: [$location]";

       };

       if ($@) {

              print $request->header(-status => '500 internal server error',

                     -type => 'text/xml');

              croak "error while logging: $@";

       } else {

              # this response code indicates that the operation was a

              # success, but the client should not expect any content

              print $request->header(-status => '204 no content',

                     -type => 'text/xml');

       }

} else {

       print $request->header(-status => '405 method not supported',

              -type => 'text/xml');

       croak "unsupported method: $method";

}