console is undefined error for Internet Explorer

Question

I m using Firebug and have some statements like   console log           in my page  In IE8  probably earlier versions too  I get script errors saying  console  is undefined  I tried putting this at the top of my page    lt script type  text javascript  gt      if   console  console    log  function         lt  script gt    still I get the errors  Any way to get rid of the errors

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In IE9  if console is not opened  this code   alert typeof console     will show  object   but this code  alert typeof console log     will throw TypeError exception  but not return undefined value   So  guaranteed version of code will look similar to this   try       if  window console  amp  amp  window console log            my console log   window console log          catch  e        my console log   function

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You can use the below to give an extra degree of insurance that you ve got all bases covered   Using typeof first will avoid any undefined errors   Using     will also ensure that the name of the type is actually the string  undefined    Finally  you ll want to add a parameter to the function signature  I chose logMsg arbitrarily  to ensure consistency  since you do pass whatever you want printed to the console to the log function   This also keep you intellisense accurate and avoids any warnings errors in your JS aware IDE   if  window console    typeof console      undefined       var console     log  function  logMsg

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For a more robust solution  use this piece of code  taken from twitter s source code       Avoid  console  errors in browsers that lack a console   function         var method      var noop   function            var methods              assert    clear    count    debug    dir    dirxml    error            exception    group    groupCollapsed    groupEnd    info    log            markTimeline    profile    profileEnd    table    time    timeEnd            timeStamp    trace    warn             var length   methods length      var console    window console   window console              while  length--            method   methods length               Only stub undefined methods          if   console method                 console method    noop

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You can use console log   if you have Developer Tools in IE8 opened and also you can use the Console textbox on script tab

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Another alternative is the typeof operator   if  typeof console     undefined         this console    log  function            Yet another alternative is to use a logging library  such as my own log4javascript

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Try  if   window console  console         An undefined variable cannot be referred directly  However  all global variables are attributes of the same name of the global context  window in case of browsers   and accessing an undefined attribute is fine   Or use if  typeof console      undefined   console       if you want to avoid the magic variable window  see  Tim Down s answer

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For IE8 or console support limited to console log  no debug  trace       you can do the following    If console OR console log undefined  Create dummy functions for console functions  trace  debug  log        window console           debug   function             Else if console log is defined  IE8  AND console debug  any other  is not defined  redirect all logging functions to console log  this allows to keep those logs    window console               debug   window console log          Not sure about the assert support in various IE versions  but any suggestions are welcome  Also posted this answer here  How can I use console logging in Internet Explorer

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console   console           debug  function           log  function

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Paste the following at the top of your JavaScript  before using the console           Protect window console method calls  e g  console is not defined on IE    unless dev tools are open  and IE doesn t define console debug        Chrome 41 0 2272 118  debug error info log warn dir dirxml table trace assert count markTimeline profile profileEnd time timeEnd timeStamp timeline timelineEnd group groupCollapsed groupEnd clear    Firefox 37 0 1  log info warn error exception debug table trace dir group groupCollapsed groupEnd time timeEnd profile profileEnd assert count    Internet Explorer 11  select log info warn error debug assert time timeEnd timeStamp group groupCollapsed groupEnd trace clear dir dirxml count countReset cd    Safari 6 2 4  debug error log info warn clear dir dirxml table trace assert count profile profileEnd time timeEnd timeStamp group groupCollapsed groupEnd    Opera 28 0 1750 48  debug error info log warn dir dirxml table trace assert count markTimeline profile profileEnd time timeEnd timeStamp timeline timelineEnd group groupCollapsed groupEnd clear      function          Union of Chrome  Firefox  IE  Opera  and Safari console methods   var methods     assert    cd    clear    count    countReset        debug    dir    dirxml    error    exception    group    groupCollapsed        groupEnd    info    log    markTimeline    profile    profileEnd        select    table    time    timeEnd    timeStamp    timeline        timelineEnd    trace    warn      var length   methods length    var console    window console   window console           var method    var noop   function         while  length--        method   methods length          define undefined methods as noops to prevent errors     if   console method         console method    noop              The function closure wrapper is to scope the variables as to not define any variables  This guards against both undefined console and undefined console debug  and other missing methods    EDIT  I noticed that HTML5 Boilerplate uses similar code in its js plugins js file  if you re looking for a solution that will  probably  be kept up-to-date

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You can use console log      directly in Firefox but not in IEs  In IEs you have to use window console

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Stub of console in TypeScript   if   window console    console         assert       gt           clear       gt           count       gt           debug       gt           dir       gt           dirxml       gt           error       gt           group       gt           groupCollapsed       gt           groupEnd       gt           info       gt           log       gt           msIsIndependentlyComposed   e  Element    gt  false      profile       gt           profileEnd       gt           select       gt           time       gt           timeEnd       gt           trace       gt           warn       gt

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I m using fauxconsole  I modified the css a bit so that it looks nicer but works very well

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Sometimes console will work in IE8 9 but fail at other times  This erratic behaviour depends on whether you have developer tools open and is described in stackoverflow question Does IE9 support console log  and is it a real function

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Noticed that OP is using Firebug with IE  so assume it s Firebug Lite   This is a funky situation as console gets defined in IE when the debugger window is opened  but what happens when Firebug is already running   Not sure  but perhaps the  firebugx js  method might be a good way to test in this situation   source   https   code google com p fbug source browse branches firebug1 2 lite firebugx js r 187      if   window console     console firebug            var names                  log    debug    info    warn    error    assert                dir   dirxml   group   groupEnd   time   timeEnd                count   trace   profile   profileEnd                     window console               for  var i   0  i  lt  names length    i              window console names i     function               updated links 12 2014

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Encountered similar problem running console log in child windows in IE9  created by window open function    It seems that in this case console is defined only in parent window and is undefined in child windows until you refresh them  Same applies to children of child windows    I deal with this issue by wrapping log in next function  below is fragment of module   getConsole  function                 if  typeof console      undefined   return console           var searchDepthMax   5              searchDepth   0              context   window opener           while    context  amp  amp  searchDepth  lt  searchDepthMax                        if  typeof context console      undefined   return context console               context   context opener              searchDepth                       return null             log  function message           var  console   this getConsole            if     console   console log message

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In my scripts  I either use the shorthand   window console  amp  amp  console log         only log if the function exists   or  if it s not possible or feasible  to edit every console log line  I create a fake console      check to see if console exists  If not  create an empty object for it     then create and empty logging function which does nothing         REMEMBER  put this before any other console log calls  window console  amp  amp   window console       amp  amp  window console log   function

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After having oh so many problems with this thing  it s hard to debug the error since if you open the developer console the error no longer happens   I decided to make an overkill code to never have to bother with this ever again   if  typeof window console      undefined       window console        if  typeof window console debug      undefined       window console debug  function        if  typeof window console log      undefined       window console log  function        if  typeof window console error      undefined       window console error  function    alert  error       if  typeof window console time      undefined       window console time  function        if  typeof window console trace      undefined       window console trace  function        if  typeof window console info      undefined       window console info  function        if  typeof window console timeEnd      undefined       window console timeEnd  function        if  typeof window console group      undefined       window console group  function        if  typeof window console groupEnd      undefined       window console groupEnd  function        if  typeof window console groupCollapsed      undefined       window console groupCollapsed  function        if  typeof window console dir      undefined       window console dir  function        if  typeof window console warn      undefined       window console warn  function         Personaly I only ever use console log and console error  but this code handles all the other functions as shown in the Mozzila Developer Network  https   developer mozilla org en-US docs Web API console  Just put that code on the top of your page and you are done forever with this

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I am only using console log in my code   So I include a very short 2 liner  var console   console        console log   console log    function

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Based on two previous answers by   Vin  cius Moraes Peter Tseng   and the documentations for   Internet Explorer  IE 10  Safari  2012  07  23   Firefox  2013  05  20   Chrome  2013  01  25   and Chrome  2012  10  04   and some of my knowledge   Here s a best effort implementation for the issue  meaning if there s a console log which actually exists  it fills in the gaps for non-existing methods via console log   For example for IE6 7 you can replace logging with alert  stupid but works  and then include the below monster  I called it console js    Feel free to remove comments as you see fit  I left them in for reference  a minimizer can tackle them     lt  -- if lte IE 7  gt   lt SCRIPT LANGUAGE  javascript  gt       window console   window console        log   function     return window alert apply window  arguments       lt  SCRIPT gt   lt   endif -- gt   lt script type  text javascript  src  console js  gt  lt  script gt    and console js                  Protect window console method calls  e g  console is not defined on IE        unless dev tools are open  and IE doesn t define console debug              function             var console    window console   window console                 var noop   function                var log   console log    noop          var start   function name    return function param    log  Start     name          param                var end   function name    return function param    log  End     name          param                 var methods                    Internet Explorer  IE 10   http   msdn microsoft com en-us library ie hh772169 v vs 85  aspx methods                assert test  message  optionalParams   clear    count countTitle   debug message  optionalParams   dir value  optionalParams   dirxml value   error message  optionalParams   group groupTitle   groupCollapsed groupTitle   groupEnd  groupTitle    info message  optionalParams   log message  optionalParams   msIsIndependentlyComposed oElementNode   profile reportName   profileEnd    time timerName   timeEnd timerName   trace    warn message  optionalParams                  assert    clear    count    debug    dir    dirxml    error    group    groupCollapsed    groupEnd    info    log    msIsIndependentlyComposed    profile    profileEnd    time    timeEnd    trace    warn                  Safari  2012  07  23    https   developer apple com library safari  documentation AppleApplications Conceptual Safari Developer Guide DebuggingYourWebsite DebuggingYourWebsite html   apple ref doc uid TP40007874-CH8-SW20                assert expression  message-object   count  title    debug  message-object    dir object   dirxml node   error message-object   group message-object   groupEnd    info message-object   log message-object   profile  title    profileEnd  title    time name   markTimeline  string    trace    warn message-object                  assert    count    debug    dir    dirxml    error    group    groupEnd    info    log    profile    profileEnd    time    markTimeline    trace    warn                  Firefox  2013  05  20    https   developer mozilla org en-US docs Web API console                debug obj1    obj2       objN    debug msg    subst1       substN    dir object   error obj1    obj2       objN    error msg    subst1       substN    group    groupCollapsed    groupEnd    info obj1    obj2       objN    info msg    subst1       substN    log obj1    obj2       objN    log msg    subst1       substN    time timerName   timeEnd timerName   trace    warn obj1    obj2       objN    warn msg    subst1       substN                   debug    dir    error    group    groupCollapsed    groupEnd    info    log    time    timeEnd    trace    warn                  Chrome  2013  01  25    https   developers google com chrome-developer-tools docs console-api                assert expression  object   clear    count label   debug object    object         dir object   dirxml object   error object    object         group object   object         groupCollapsed object   object         groupEnd    info object    object         log object    object         profile  label    profileEnd    time label   timeEnd label   timeStamp  label    trace    warn object    object                        assert    clear    count    debug    dir    dirxml    error    group    groupCollapsed    groupEnd    info    log    profile    profileEnd    time    timeEnd    timeStamp    trace    warn                 Chrome  2012  10  04    https   developers google com web-toolkit speedtracer logging-api                markTimeline String                  markTimeline               assert  noop  clear  noop  trace  noop  count  noop  timeStamp  noop  msIsIndependentlyComposed  noop              debug  log  info  log  log  log  warn  log  error  log              dir  log  dirxml  log  markTimeline  log              group  start  group    groupCollapsed  start  groupCollapsed    groupEnd  end  group                profile  start  profile    profileEnd  end  profile                time  start  time    timeEnd  end  time                       for  var method in methods                if   methods hasOwnProperty method   amp  amp    method in console         define undefined methods as best-effort methods                 console method    methods method

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For debugging in IE  check out this log4javascript

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if  typeof console     undefined       this console         log  function           info  function           error  function           warn  function

[javascript] 'console' is undefined error for Internet Explorer

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