IEWebDeveloper offers you a debug console, which can be used on same interface as FireBug (console.log, console.debug, and so on...). you can log messages from JavaScript in your web page directly to the IEWebDeveloper console.
Demo
Click here!
Prevent calls to console.log() from causing errors in the other browsers
In firefox, you can use firebug to log message. If you want to prevent calls to console.log() from causing errors in the other browsers , then insert this line of code into any page, like so:
<script language="javascript" type="text/javascript" src="/path/firebugx.js"></script>
Firebugx.js is usually located in this directory: "c:\program files\ieinspector\IEWebDeveloper\ConsoleAPI". You also can grab firebugx.js here and just copy and paste it into your code.
Console Logging Functions
The following content is copied from the FireBug document.
FireBug makes a console object available to all web pages. This object has the following functions:
Basic Logging
console.log("message" [,objects]) - Logs a string to the console. The string may contain any of the patterns described below in the "String Formatting" section. The objects passed after the string will be substituted for each of the patterns in the string in order.
Logging Levels
It is often useful to separate messages according to different levels of severity. There are four different functions for this purpose. In addition to the visual separation, these functions are also different from log in that they automatically include a link to the line number in the source where they are called.
console.debug("message" [,objects]) - Logs a debug message.
console.info("message" [,objects]) - Logs an informative message.
console.warn("message" [,objects]) - Logs a warning.
console.error("message" [,objects]) - Logs an error.
Assertions
Assertions are a great way to enforce rules in your code. The console object includes a set a common types of assertion functions, and also allows you to write your own.
console.assert(a, "message" [,objects]) - Asserts that an a is true.
console.assertEquals(a, b, "message" [,objects]) - Asserts that a is equal to b.
console.assertNotEquals(a, b, "message" [,objects]) - Asserts that a is not equal to b.
console.assertGreater(a, b, "message" [,objects]) - Asserts that a is greater than b.
console.assertNotGreater(a, b, "message" [,objects]) - Asserts that a is not greater than b.
console.assertLess(a, b, "message" [,objects]) - Asserts that a is less than b.
console.assertNotLess(a, b, "message" [,objects]) - Asserts that a is not less than b.
console.assertContains(a, b, "message" [,objects]) - Asserts that a is in the array b.
console.assertNotContains(a, b, "message" [,objects]) - Asserts that a is not in the array b.
console.assertTrue(a, "message" [,objects]) - Asserts that a is equal to true.
console.assertFalse(a, "message" [,objects]) - Asserts that a is equal to false.
console.assertNull(a, "message" [,objects]) - Asserts that a is equal to null.
console.assertNotNull(a, "message" [,objects]) - Asserts that a is not equal to null.
console.assertUndefined(a, "message" [,objects]) - Asserts that a is equal to undefined.
console.assertNotUndefined(a, "message" [,objects]) - Asserts that a is not equal to undefined.
console.assertInstanceOf(a, b, "message" [,objects]) - Asserts that a is an instance of type b.
console.assertNotInstanceOf(a, b, "message" [,objects]) - Asserts that a is not an instance of type b.
console.assertTypeOf(a, b, "message" [,objects]) - Asserts that the type of a is equal to the string b.
console.assertNotTypeOf(a, b, "message" [,objects]) - Asserts that the type of a is not equal to the string b.
Measurement
The following functions allow you to measure certain aspects of your code.
console.trace() - Logs a stack trace showing the point of execution where this is called. (Not supported in IEWebDeveloper)
console.time("name") - Begins a timer and gives it a unique name.
console.timeEnd("name") - Stops the timer with the given name and logs the number of milliseconds that have ellapsed since it was started.
console.count("name") - Logs the number of times that the line of code where this is called has been executed.
String Formatting
All of the console logging functions can format a string with any of the following patterns:
%s - Formats the object as a string.
%d, %i, %l, %f - Formats the object as a number.
%o - Formats the object as a hyperlink to the inspector.
%1.o, %2.0, etc.. - Formats the object as an interactive table of its properties.(Not supported in IEWebDeveloper)
%.o - Formats the object as an array of its property names.
%x - Formats the object as an interactive XML markup tree.(Not supported in IEWebDeveloper)
%1.x, %2.x, etc.. - Formats the object as an interactive XML markup tree with n levels expanded.(Not supported in IEWebDeveloper)
If you need to include a real % symbol, you can escape it with a backslash like so: "\%". (Not supported in IEWebDeveloper)
Command Line Functions (Not supported in IEWebDeveloper)
The following built-in functions can be accessed from the command line:
$("id") - A shortcut for document.getElementById().
$$("css") - Returns an array of elements that match a CSS selector.
$x("xpath") - Returns an array of elements that match an XPath selector.
$0 - Variable containing the most recently inspected object .
$1 - Variable containing the next most recently inspected object .
$n(5) - Returns the nth most recently inspected object that has been inspected.
inspect(object) - Displays an object in the Inspector.
dir(object) - Returns an array of property names on an object.
clear() - Clears the console.
Special thanks
This is because FireBug is MPL and most of the consoleapi.js and firebugx.js source code is quoted from FireBug. Special thanks for Joe Hewitt, the author of FireBug.