log() outputs a message to the web console. The
message may be a single string (with optional substitution values), or it may be any one
Note:This feature is available in Web Workers.
console.log(obj1 [, obj2, ..., objN]); console.log(msg [, subst1, ..., substN]);
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 open the console.
msg. This gives you additional control over the format of the output.
You might ask yourself what's the difference between
Another useful difference in Chrome exists when sending DOM elements to the console.
console.logprints the element in an HTML-like tree
console.dirprints the element in a JSON-like tree
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.
This way you are sure you are seeing the value of
obj at the moment you
log it. Otherwise, many browsers provide a live view that constantly updates as values
change. This may not be what you want.
The definition of 'console.log()' in that specification.
|Living Standard||Initial definition|
BCD tables only load in the browser
- 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