How can I get a JavaScript stack trace when I throw an exception

Question

If I throw a JavaScript exception myself  eg  throw  AArrggg    how can I get the stack trace  in Firebug or otherwise    Right now I just get the message   edit  As many people below have posted  it is possible to get a stack trace for a JavaScript exception but I want to get a stack trace for my exceptions   For example   function foo         bar 2     function bar n        if  n  lt  2          throw  Oh no   n  is too small       bar n-1       When foo is called  I want to get a stack trace which includes the calls to foo  bar  bar

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With Chrome browser  you can use console trace method  https   developer chrome com devtools docs console-api consoletraceobject

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at least in Edge 2021   console groupCollapsed  jjjjjjjjjjjjjjjjj       console trace       try           throw  quot kuku quot        catch e            console log e stack        console groupEnd   traceUntillMe    and you are done my friend

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In Google Chrome  version 19 0 and beyond   simply throwing an exception works perfectly  For example      file  code js  line numbers shown     188  function fa     189     console log  executing fa       190     fb    191    192  193  function fb     194     console log  executing fb       195     fc   196    197  198  function fc     199     console log  executing fc       200     throw  error in fc     201    202  203  fa      will show the stack trace at the browser s console output   executing fa                            code js 189 executing fb                            code js 194 executing fc                            cdoe js 199    this is your stack trace    Uncaught error in fc                    code js 200     fc                                  code js 200     fb                                  code js 195     fa                                  code js 190      anonymous function                 code js 203   Hope this help

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Wow - I don t see a single person in 6 years suggesting that we check first to see if stack is available before using it  The worst thing you can do in an error handler is throw an error because of calling something that doesn t exist   As others have said  while stack is mostly safe to use now it is not supported in IE9 or earlier   I log my unexpected errors and a stack trace is pretty essential  For maximum support I first check to see if Error prototype stack exists and is a function  If so then it is safe to use error stack            window onerror   function  message  string  filename   string  line   number                                      col   number  error   Error                           always wrap error handling in a try catch             try                                   get the stack trace  and if not supported make our own the best we can                 var msg    typeof Error prototype stack     function     error stack                               NO-STACK     filename         line         col       message                      log errors here or whatever you re planning on doing                 alert msg                             catch  err                                            Edit  It appears that since stack is a property and not a method you can safely call it even on older browsers  I m still confused because I was pretty sure checking Error prototype worked for me previously and now it doesn t - so I m not sure what s going on

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A good  and simple  solution as pointed out in the comments on the original question is to use the stack property of an Error object like so   function stackTrace         var err   new Error        return err stack      This will generate output like this   DBX Utils stackTrace http   localhost 49573 assets js scripts js 44 DBX Console Debug http   localhost 49573 assets js scripts js 9  success http   localhost 49573  462 x Callbacks c http   localhost 49573 assets js jquery-1 10 2 min js 4 x Callbacks p fireWith http   localhost 49573 assets js jquery-1 10 2 min js 4 k http   localhost 49573 assets js jquery-1 10 2 min js 6  send r http   localhost 49573 assets js jquery-1 10 2 min js 6   Giving the name of the calling function along with the URL and line number  its calling function  and so on   I have a really elaborate and pretty solution that I have devised for a project I am currently working on and I have extracted and reworked it a bit to be generalized  Here it is    function context          Only global namespace      var Console               Settings         settings                debug                    alwaysShowURL  false                  enabled  true                  showInfo  true                            stackTrace                    enabled  true                  collapsed  true                  ignoreDebugFuncs  true                  spacing  false                                        String formatting prototype function      if   String prototype format            String prototype format   function                  var s   this toString                    args   typeof arguments 0                   args      string     args     number     args    arguments   arguments 0                if   arguments length                  return s              for  arg in args                  s   s replace RegExp         arg           gi    args arg                return s                          String repeating prototype function      if   String prototype times            String prototype times   function                  var s   this toString                    tempStr                       times   arguments 0               if   arguments length                  return s              for  var i   0  i  lt  times  i                    tempStr    s              return tempStr                          Commonly used functions     Console debug   function              if  Console settings debug enabled                var args     typeof arguments      undefined     Array prototype slice call arguments  0                         sUA   navigator userAgent                  currentBrowser                         firefox   firefox gi test sUA                       webkit   webkit gi test sUA                                      aLines   Console stackTrace   split   n                    aCurrentLine                  iCurrIndex     currentBrowser webkit    3   2                   sCssBlack    color black                    sCssFormat    color  0   font-weight bold                    sLines                    if  currentBrowser firefox                  aCurrentLine   aLines iCurrIndex  replace            1    split                   else if  currentBrowser webkit                  aCurrentLine   aLines iCurrIndex  replace  at        replace          replace        gi       replace         d     d       1  2  3   split                       Show info if the setting is true and there s no extra trace  would be kind of pointless               if  Console settings debug showInfo  amp  amp   Console settings stackTrace enabled                    var sFunc   aCurrentLine 0  trim                        sURL   aCurrentLine 1  trim                        sURL      Console settings debug alwaysShowURL  amp  amp  context location href    sURL     this page    sURL                       sLine   aCurrentLine 2  trim                        sCol                   if  currentBrowser webkit                      sCol   aCurrentLine 3  trim                     console info   cOn line  c 0  c 1  c 2  c of  c 3  c inside the  c 4  c function   format sLine    currentBrowser webkit       column            currentBrowser webkit    sCol        sURL  sFunc                                sCssBlack  sCssFormat format  red                                 sCssBlack  sCssFormat format  purple                                 sCssBlack  sCssFormat format  green                                 sCssBlack  sCssFormat format  blue                                 sCssBlack                                 If the setting permits  get rid of the two obvious debug functions  Console debug and Console stackTrace               if  Console settings stackTrace ignoreDebugFuncs                       In WebKit  Chrome at least   there s an extra line at the top that says  Error  so adjust for this                  if  currentBrowser webkit                      aLines shift                    aLines shift                    aLines shift                               sLines   aLines join   Console settings stackTrace spacing      n n      n    trim                 trace   typeof trace      undefined    trace   true              if  typeof console      undefined                     for  var arg in args                      console debug args arg                     if  Console settings stackTrace enabled                        var sCss    color red  font-weight  bold                            sTitle     c Stack Trace        times 70                        if  Console settings stackTrace collapsed                          console groupCollapsed sTitle  sCss                       else                         console group sTitle  sCss                        console debug   c    sLines   color   666666  font-style  italic                          console groupEnd                                                        Console stackTrace   function              var err   new Error            return err stack             context Console   Console     window     Check it out on GitHub  currently v1 2   You can use it like Console debug  Whatever    and it will  depending on the settings in Console  print the output and a stack trace  or just simple info nothing extra at all   Here s an example     Make sure to play around with the settings in the Console object  You can add spacing between the lines of the trace and turn it off entirely  Here it is with Console trace set to false     You can even turn off the first bit of info shown  set Console settings debug showInfo to false  or disable debugging entirely  set Console settings debug enabled to false  so you never have to comment out a debug statement again  Just leave them in and this will do nothing

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Using console error e stack  Firefox only shows the stacktrace in logs  Chrome also shows the message  This can be a bad surprise if the message contains vital information  Always log both

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I don t think there s anything built in that you can use however I did find lots of examples of people rolling their own    DIY javascript stack trace A Javascript stacktrace in any browser

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This polyfill code working in modern  2017  browsers  IE11  Opera  Chrome  FireFox  Yandex    printStackTrace  function          var err   new Error        var stack   err stack      old opera   err stacktrace        IE11   console trace   console trace      no stack info        return stack      Other answers    function stackTrace       var err   new Error      return err stack      not working in IE 11    Using arguments callee caller - not working in strict mode in any browser

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An update to Eugene s answer  The error object must be thrown in order for IE  specific versions   to populate the stack property  The following should work better than his current example  and should avoid returning undefined when in IE   function stackTrace       try       var err   new Error        throw err      catch  err        return err stack          Note 1  This sort of thing should only be done when debugging  and disabled when live  especially if called frequently  Note 2  This may not work in all browsers  but seems to work in FF and IE 11  which suits my needs just fine

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Here is an answer that gives you max performance  IE 6   and max compatibility  Compatible with IE 6    x000D   x000D      function stacktrace  log result     x000D       var trace result  x000D         IE 6 through 9 compatibility x000D         this is NOT an all-around solution because x000D         the callee property of arguments is depredicated x000D         cc on x000D          theese fancy conditinals make this code only run in IE x000D       trace result    function st2 fTmp    x000D           credit to Eugene for this part of the code x000D        return  fTmp        x000D         st2 fTmp caller  concat  fTmp toString   split      0  substring 9          fTmp arguments join               x000D          arguments callee caller   x000D       if  log result     the ancient way to log to the console x000D        Debug write  trace result    x000D       return trace result  x000D          x000D       console   console    Console     just in case x000D       if    console  amp  amp  console trace      log result   x000D           for better performance in IE 10 x000D        var STerror new Error    x000D        var unformated  STerror stack    STerror stacktrace   x000D        trace result     u25BC console trace    unformated substring unformated indexOf   n  unformated indexOf   n       x000D         else   x000D           IE 11  and everyone else compatibility x000D        trace result   console trace    x000D         x000D       if  log result  x000D        console log  trace result    x000D        x000D       return trace result  x000D        x000D     test code x000D   function testfunc    x000D   document write    lt pre gt     stacktrace  false       lt  pre gt      x000D        x000D   x000D   x000D

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You can access the stack  stacktrace in Opera  properties of an Error instance even if you threw it  The thing is  you need to make sure you use throw new Error string   don t forget the new instead of throw string   Example   try       0      catch  e        var myStackTrace   e stack    e stacktrace

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Note that chromium chrome  other browsers using V8   and also Firefox do have a convenient interface to get a stacktrace through a stack property on Error objects   try         Code throwing an exception   catch e      console log e stack       It applies for the base exceptions as well as for the ones you throw yourself   Considered that you use the Error class  which is anyway a good practice    See details on V8 documentation

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Edit 2  2017    In all modern browsers you can simply call  console trace     MDN Reference   Edit 1  2013    A better  and simpler  solution as pointed out in the comments on the original question is to use the stack property of an Error object like so   function stackTrace         var err   new Error        return err stack      This will generate output like this   DBX Utils stackTrace http   localhost 49573 assets js scripts js 44 DBX Console Debug http   localhost 49573 assets js scripts js 9  success http   localhost 49573  462 x Callbacks c http   localhost 49573 assets js jquery-1 10 2 min js 4 x Callbacks p fireWith http   localhost 49573 assets js jquery-1 10 2 min js 4 k http   localhost 49573 assets js jquery-1 10 2 min js 6  send r http   localhost 49573 assets js jquery-1 10 2 min js 6   Giving the name of the calling function along with the URL  its calling function  and so on   Original  2009    A modified version of this snippet may somewhat help   function stacktrace        function st2 f        return  f                 st2 f caller  concat  f toString   split      0  substring 9          f arguments join                     return st2 arguments callee caller

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function   function print call stack err        var stack   err stack      console error stack       use case        try           aaa bbb   error throw here             catch  err            print call stack err

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Kind of late to the party  but  here is another solution  which autodetects if arguments callee is available  and uses new Error   stack if not  Tested in chrome  safari and firefox   2 variants - stackFN n  gives you the name of the function n away from the immediate caller  and stackArray   gives you an array  stackArray   0  being the immediate caller   Try it out at http   jsfiddle net qcP9y 6      returns the name of the function at caller-N    stackFN      the immediate caller to stackFN    stackFN 0    the immediate caller to stackFN    stackFN 1    the caller to stackFN s caller    stackFN 2    and so on    eg console log stackFN   JSON stringify arguments   called by  stackFN 1   returns  retval   function stackFN n        var r   n   n   0  f   arguments callee avail typeof f      function           s2 s   avail   false   new Error   stack      if  s            var tl function x    s   s substr s indexOf x    x length             tr   function  x   s   s substr 0  s indexOf x  - x length             while  r--  gt   0                tl                         tl   at             tr               return s        else           if   avail  return null          s    f   arguments callee          while  r gt  0                s    caller               r--                       eval s           return f toString   split      0  trim   split      1              same as stackFN   but returns an array so you can work iterate or whatever  function stackArray         var res    f   arguments callee avail typeof f      function           s2 s   avail   false   new Error   stack      if  s            var tl function x    s   s substr s indexOf x    x length             tr   function  x   s   s substr 0  s indexOf x  - x length             while  s indexOf      gt  0                tl                   s2     s              tl   at                 tr                   res push s               s    s2                  else           if   avail  return null          s    f   arguments callee caller          eval s           while  f                res push f toString   split      0  trim   split      1                s    caller               eval s                       return res      function apple makes stuff         var retval    iPhones       var stk   stackArray         console log  function   stk 0      was called by  stk 1             console log stk       console log stackFN   JSON stringify arguments   called by  stackFN 1   returns  retval       return retval       function apple makes         return apple makes stuff  really nice stuff       function apple          return apple makes          apple

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You could use this library http   www stacktracejs com    It s very good  From documentation     You can also pass in your own Error to get a stacktrace not available   in IE or Safari 5-    lt script type  text javascript  src  https   rawgithub com stacktracejs stacktrace js master stacktrace js  gt  lt  script gt   lt script type  text javascript  gt      try              error producing code       catch e            var trace   printStackTrace  e  e            alert  Error  n     Message      e message     nStack trace  n    trace join   n                do something else with error        lt  script gt

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In Firefox it seems that you don t need to throw the exception   It s sufficient to do  e   new Error    console log e stack

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Just try  throw new Error  some error here     This works pretty well for chrome

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I had to investigate an endless recursion in smartgwt with IE11  so in order to investigate deeper  I needed a stack trace  The problem was  that I was unable to use the dev console  because the reproduction was more difficult that way  Use the following in a javascript method   try  null toString      catch e    alert e stack

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lt script type  text javascript  src  https   rawgithub com stacktracejs stacktrace js master stacktrace js  gt  lt  script gt   lt script type  text javascript  gt      try              error producing code       catch e            var trace   printStackTrace  e  e            alert  Error  n     Message      e message     nStack trace  n    trace join   n                do something else with error        lt  script gt    this script will show the error

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It is easier to get a stack trace on Firefox than it is on IE but fundamentally here is what you want to do   Wrap the  problematic  piece of code in a try catch block   try          some code that doesn t work     var t   null      var n   t not a value        catch e        If you will examine the contents of the  error  object it contains the following fields   e fileName   The source file   page where the issue came from e lineNumber   The line number in the file page where the issue arose  e message   A simple message describing what type of error took place e name   The type of error that took place  in the example above it should be  TypeError  e stack   Contains the stack trace that caused the exception  I hope this helps you out

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If you have firebug  there s a break on all errors option in the script tab  Once the script has hit your breakpoint  you can look at firebug s stack window

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This will give a stack trace  as array of strings  for modern Chrome  Opera  Firefox and IE10   function getStackTrace         var stack     try       throw new Error            catch  error        stack   error stack               stack   stack split   n   map function  line    return line trim          return stack splice stack 0      Error    2   1       Usage   console log getStackTrace   join   n       It excludes from the stack its own call as well as title  Error  that is used by Chrome and Firefox  but not IE    It shouldn t crash on older browsers but just return empty array  If you need more universal solution look at stacktrace js  Its list of supported browsers is really impressive but to my mind it is very big for that small task it is intended for  37Kb of minified text including all dependencies

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one way to get a the real stack trace on Firebug is to create a real error like calling an undefined function   function foo b     if  typeof b      string           undefined Error type to get the call stack     throw new ChuckNorrisError  Chuck Norris catches you            function bar a     foo a      foo 123     Or use console error   followed by a throw statement since console error   shows the stack trace

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function stacktrace      return  new Error    stack split   n   reverse   slice 0 -2  reverse   join   n

[javascript] How can I get a JavaScript stack trace when I throw an exception?

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