console.log()
The console.log()
method outputs a message to the web console.
The message may be a single string (with optional substitution values), or it may be any one
or more JavaScript objects.
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 open the console. 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.
Difference between log() and 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 treeconsole.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. Otherwise, many browsers provide a live view that constantly updates as values
change. This may not be what you want.
Specifications
Specification |
---|
Console Standard # log |
Browser compatibility
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