How can I use console logging in Internet Explorer?

Is there a console logger for IE? I'm trying to log a bunch of tests/assertions to the console but I can't do this in IE.

You can access IE8 script console by launching the "Developer Tools" (F12). Click the "Script" tab, then click "Console" on the right.

From within your JavaScript code, you can do any of the following:

<script type="text/javascript">
    console.log('some msg');
    console.info('information');
    console.warn('some warning');
    console.error('some error');
    console.assert(false, 'YOU FAIL');
</script>

Also, you can clear the Console by calling console.clear().

NOTE: It appears you must launch the Developer Tools first then refresh your page for this to work.

Since version 8, Internet Explorer has its own console, like other browsers. However, if the console is not enabled, the console object does not exist and a call to console.log will throw an error.

Another option is to use log4javascript (full disclosure: written by me), which has its own logging console that works in all mainstream browsers, including IE >= 5, plus a wrapper for the browser's own console that avoids the issue of an undefined console.

Extremely important if using console.log() in production:

if you end up releasing console.log() commands to production you need to put in some kind of fix for IE - because console is only defined when in F12 debugging mode.

if (typeof console == "undefined") {
    this.console = { log: function (msg) { alert(msg); } };
}

[obviously remove the alert(msg); statement once you've verified it works]

See also https://stackoverflow.com/questions/3326650/console-is-undefined-error-for-internet-explorer for other solutions and more details

There is Firebug Lite which gives a lot of Firebug functionality in IE.

Simple IE7 and below shim that preserves Line Numbering for other browsers:

/* console shim*/
(function () {
    var f = function () {};
    if (!window.console) {
        window.console = {
            log:f, info:f, warn:f, debug:f, error:f
        };
    }
}());

In his book, "Secrets of Javascript Ninja", John Resig (creator of jQuery) has a really simple code which will handle cross-browser console.log issues. He explains that he would like to have a log message which works with all browsers and here is how he coded it:

function log() {
  try {
    console.log.apply(console, arguments);
  } catch(e) {
  try {
    opera.postError.apply(opera, arguments);
  }
  catch(e) {
    alert(Array.prototype.join.call( arguments, " "));
  }
}

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.

You can use cross-browser wrapper: https://github.com/MichaelZelensky/log.js

For older version of IE (before IE8), it is not straight forward to see the console log in IE Developer Toolbar, after spending hours research and trying many different solutions, finally, the following toolbar is great tool for me:

• http://www.my-debugbar.com/wiki/CompanionJS/Installing

The main advantage of this is providing a console for IE6 or IE7, so you can see what are the error (in the console log)

• Note:

• It is free
• screen shot of the toolbar

I've been always doing something like this:

var log = (function () {
  try {
    return console.log;
  }
  catch (e) {
    return function () {};
  }
}());

and from that point just always use log(...), don't be too fancy using console.[warn|error|and so on], just keep it simple. I usually prefer simple solution then fancy external libraries, it usually pays off.

simple way to avoid problems with IE (with non existing console.log)