Outputs a message to the Web Console.

Note: This feature is available in Web Workers.

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. Please be warned that if you log objects in the latest versions of Chrome and Firefox what you get logged on the console is a reference to the object, which is not necessarily the 'value' of the object at the moment in time you call console.log(), but it is the value of the object at the moment you click it open.
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

FeatureChromeEdgeFirefoxInternet ExplorerOperaSafari
Basic support Yes1248 Yes Yes
Substitution strings Yes1 Yes9102 ? ?
FeatureAndroid webviewChrome for AndroidEdge mobileFirefox for AndroidOpera AndroidiOS SafariSamsung Internet
Basic support ? ? Yes4 ? ? ?
Substitution strings ? ? Yes9 ? ? ?

1. In version 28, 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.

Logging objects

Don't use console.log(obj);,
use console.log(JSON.parse(JSON.stringify(obj)));.

This way you are sure you are seeing the value of obj at the moment you log it.

See also