node.body[i].print（stream）
}
varinnerFuncCode=stream.toString（）;
//清除trycatch中定义的多余语句
tryCatchAST.body[0].body.splice（0,tryCatchAST.body[0].body.length）;
//用trycatch包裹函数代码
varinnerTyrCatchNode=UglifyJS.parse（innerFuncCode,{toplevel:
tryCatchAST.body[0]}）;
//获取函数壳
node.body.splice（0,node.body.length）;
//生成有trycatch的函数
returnUglifyJS.parse（innerTyrCatchNode.print_to_string（）,{toplevel:
node}）;
}
}）;
inputAST.transform（transfer）;
varoutputCode=inputAST.print_to_string（{beautify:
true}）;
returnoutputCode;
}
module.exports.globalFuncTryCatch=globalFuncTryCatch;
借助于globalFuncTryCatch，我们对每个函数进行自动化地添加trycatch语句，并使用自定义的错误处理函数：
globalFuncTryCatch（inputCode,function（error）{
//此处是异常处理代码，可以上报并记录日志
console.log（error）;
}）;
通过将globalFuncTryCatch功能集成到构建工具中，我们就可以对目标Javascript文件进行trycatch处理。
综上所述：
当静态资源服务器可以添加Access-Control-Allow-Origin:
*时，我们可以直接使用window.onError进行全局异常捕获；当静态资源服务器不受控制，window.onError失效，我们可以借助AST技术，自动化地对全部目标Javascript函数添加trycatch来捕获所有异常。
参考文档：
CaptureandreportJavaScripterrorswithwindow.onerror
onerrorisaspecialbrowsereventthatfireswheneveranuncaughtJavaScripterrorhasbeenthrown.It’soneoftheeasiestwaystologclient-sideerrorsandreportthemtoyourservers.It’salsooneofthemajormechanismsbywhichSentry’sclientJavaScriptintegration（raven-js）works.
Youlistentotheonerroreventbyassigningafunctiontowindow.onerror:
window.onerror=function（msg,url,lineNo,columnNo,error）{
//...handleerror...
returnfalse;
}
Whenanerroristhrown,thefollowingargumentsarepassedtothefunction:
msg–Themessageassociatedwiththeerror,e.g.“UncaughtReferenceError:
fooisnotdefined”
url–TheURLofthescriptordocumentassociatedwiththeerror,e.g.“/dist/app.js”
lineNo–Thelinenumber（ifavailable）
columnNo–Thecolumnnumber（ifavailable）
error–TheErrorobjectassociatedwiththiserror（ifavailable）
Thefirstfourargumentstellyouinwhichscript,line,andcolumntheerroroccurred.Thefinalargument,Errorobject,isperhapsthemostvaluable.Let’slearnwhy.
TheErrorobjectanderror.stack
AtfirstglancetheErrorobjectisn’tveryspecial.Itcontains3standardizedproperties:
message,fileName,andlineNumber.Redundantvaluesthatalreadyprovidedtoyouviawindow.onerror.
Thevaluablepartisanon-standardproperty:
Error.prototype.stack.Thisstackpropertytellsyouatwhatsourcelocationeachframeoftheprogramwaswhentheerroroccurred.Thestacktracecanbeacriticalpartofdebugginganerror.Anddespitebeingnon-standard,thispropertyisavailableineverymodernbrowser.
Here’sanexampleoftheErrorobject’sstackpropertyinChrome46:
"Error:
foobar\natnewbar（:
241:
11）\natfoo（:
245:
5）\nat:
250:
5\nat:
251:
3\nat:
267:
4\natcallFunction（:
229:
33）\nat:
239:
23\nat:
240:
3\natObject.InjectedScript._evaluateOn（:
875:
140）\natObject.InjectedScript._evaluateAndWrap（:
808:
34）"
Hardtoread,right?
Thestackpropertyisactuallyjustanunformattedstring.
Here’swhatitlookslikeformatted:
Error:
foobar
atnewbar（:
241:
11）
atfoo（:
245:
5）
atcallFunction（:
229:
33）
atObject.InjectedScript._evaluateOn（:
875:
140）
atObject.InjectedScript._evaluateAndWrap（:
808:
34）
Onceit’sbeenformatted,it’seasytoseehowthestackpropertycanbecriticalinhelpingtodebuganerror.
There’sjustonesnag:
thestackpropertyisnon-standard,anditsimplementationdiffersamongbrowsers.Forexample,here’sthesamestacktracefromInternetExplorer11:
Error:
foobar
atbar（Unknownscriptcode:
2:
5）
atfoo（Unknownscriptcode:
6:
5）
atAnonymousfunction（Unknownscriptcode:
11:
5）
atAnonymousfunction（Unknownscriptcode:
10:
2）
atAnonymousfunction（Unknownscriptcode:
1:
73）
Notonlyistheformatofeachframedifferent,theframesalsohavelessdetail.Forexample,Chromeidentifiesthatthenewkeywordhasbeenused,andhasgreaterinsightintoevalinvocations.AndthisisjustIE11vsChrome–otherbrowserssimilarhavevaryingformatsanddetail.
Luckily,therearetoolsouttherethatnormalizestackpropertiessothatitisconsistentacrossbrowsers.Forexample,raven-jsusesTraceKittonormalizeerrorstrings.There’salsostacktrace.jsandafewotherprojects.
Browsercompatibility
window.onerrorhasbeenavailableinbrowsersforsometime–you’llfinditinbrowsersasoldasIE6andFirefox2.
Theproblemisthateverybrowserimplementswindow.onerrordifferently.Particularly,inhowmanyargumentsaresenttototheonerrorlistener,andthestructureofthosearguments.
Here’satableofwhichargumentsarepassedtoonerrorinmostbrowsers:
BrowserMessageURLlineNocolNoerrorObj
Firefox42
Chrome46
AndroidBrowser4.4
Edge
IE11
IE10
IE9,8
Safari9
iOS9
You’llnoticethatthelatestApplebrowsers–SafariandiOS–don’tsupporta5therrorobjectargument.AndwhilethefinalversionofInternetExplorer（11）supportstheerrorobject,Microsoft’slatestbrowser,Edge,doesnot.
Withouttheerrorobject,thereisnostacktraceproperty.Thismeansthatthesebrowserscannotretrievevaluablestackinformationfromerrorscaughtbyonerror.
Polyfillingwindow.onerrorwithtry/catch
Butthereisaworkaround–youcanwrapcodeinyourapplicationinsideatry/catchandcatchtheerroryourself.Thiserrorobjectwillcontainourcovetedstackpropertyineverymodernbrowser.
Considerthefollowinghelpermethod,invoke,whichcallsafunctiononanobjectwithanarrayofarguments:
functioninvoke（obj,method,args）{
returnobj[method].apply（this,args）;
}
invoke（Math,'max',[1,2]）;//returns2
Here’sinvokeagain,thistimewrappedintry/catch,inordertocaptureanythrownerror:
functioninvoke（obj,method,args）{
try{
returnobj[method].apply（this,args）;
}catch（e）{
captureError（e）;//reporttheerror
throwe;//re-throwtheerror
}
}
invoke（Math,'highest',[1,2]）;//throwserror,nomethodMath.highest
Ofcourse,doingthismanuallyeverywhereisprettycumbersome.Youcanmakeiteasierbycreatingagenericwrapperutilityfunction:
functionwrapErrors（fn）{
//don'twrapfunctionmorethanonce
if（!
fn.__wrapped__）{
fn.__wrapped__=function（）{
try{
returnfn.apply（this,arguments）;
}catch（e）{
captureError（e）;//reporttheerror
throwe;//re-throwtheerror
}
};
}
returnfn.__wrapped__;
}
varinvoke=wrapErrors（function（obj,method,args）{
returnobj[method].apply（this,args）;
}）;
invoke（Math,'highest',[1,2]）;//nomethodMath.highest
BecauseJavaScriptissinglethreaded,youdon
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