console.log

Outputs a message to the Web Console.

Syntax

console.log(obj1 [, obj2, ..., objN]);
console.log(msg [, subst1, ..., substN]);

Parameters

obj1 ... objN

A list of JavaScript objects to output. The string representations of each of these objects are appended together in the order listed and output.

msg

A JavaScript string containing zero or more substitution strings.

subst1 ... substN

JavaScript objects with which to replace substitution strings within msg. This gives you additional control over the format of the output.

See Outputting text to the console in the documentation of console for details.

Specifications

Specification	Status	Comment
Console API The definition of 'console.log()' in that specification.	Living Standard	Initial definition

Browser compatibility

[1] If a negative value is passed to %d, it will be rounded down to the closest negative integer, so -0.1 becomes -1.

[2] %c is not supported, %d will render as 0 when it is not a number.

Difference with console.dir()

You might ask yourself what's the difference between console.dir() and console.log().

Another useful difference in Chrome exists when sending DOM elements to the console.

Notice:

• console.log prints the element in an HTML-like tree
• console.dir prints the element in a JSON-like tree

Specifically, console.log gives special treatment to DOM elements, whereas console.dir does not. This is often useful when trying to see the full representation of the DOM JS object.

There's more information in the Chrome Console API reference about this and other functions.

See also

• Opera Dragonfly documentation: Console
• MSDN: Using the F12 Tools Console to View Errors and Status
• Firebug wiki: Console API - Firebug supports additional features in its console.log() implementation, such as styled logging.
• NodeJS: Console API