Console Standard
Console
Living Standard — Last Updated
15 March 2026
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Tests:
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(non-normative)
简体中文
한국어
Abstract
This specification defines APIs for console debugging facilities.
Status
This specification is an early work in progress that welcomes feedback to refine toward more
precise and compatible definitions. It is also the editors' first specification, so please be kind
and constructive.
Please join us in the
issue tracker
for more
discussion.
1.
Namespace
console
[Exposed=*]
namespace
console
{ // but see namespace object requirements below
// Logging
undefined
assert
optional
boolean
condition
false
any
...
data
);
undefined
clear
();
undefined
debug
any
...
data
);
undefined
error
any
...
data
);
undefined
info
any
...
data
);
undefined
log
any
...
data
);
undefined
table
optional
any
tabularData
optional
sequence
DOMString
properties
);
undefined
trace
any
...
data
);
undefined
warn
any
...
data
);
undefined
dir
optional
any
item
optional
object
options
);
undefined
dirxml
any
...
data
);
// Counting
undefined
count
optional
DOMString
label
= "default");
undefined
countReset
optional
DOMString
label
= "default");
// Grouping
undefined
group
any
...
data
);
undefined
groupCollapsed
any
...
data
);
undefined
groupEnd
();
// Timing
undefined
time
optional
DOMString
label
= "default");
undefined
timeLog
optional
DOMString
label
= "default",
any
...
data
);
undefined
timeEnd
optional
DOMString
label
= "default");
};
For historical reasons,
console
is lowercased.
It is important that
console
is always visible and usable to scripts, even if the developer
console has not been opened or does not exist.
For historical web-compatibility reasons, the
namespace object
for
console
must have as
its [[Prototype]] an empty object, created as if by
ObjectCreate
%ObjectPrototype%
), instead of
%ObjectPrototype%
1.1.
Logging functions
1.1.1.
assert(
condition
, ...
data
If
condition
is true, return.
Let
message
be a string without any formatting specifiers indicating generically an assertion
failure (such as "Assertion failed").
If
data
is
empty
append
message
to
data
Otherwise:
Let
first
be
data
[0].
If
first
is not a String
, then
prepend
message
to
data
Otherwise:
Let
concat
be the concatenation of
message
, U+003A (:), U+0020 SPACE, and
first
Set
data
[0] to
concat
Perform
Logger
("assert",
data
).
1.1.2.
clear()
Empty
the appropriate
group stack
If possible for the environment, clear the console. (Otherwise, do nothing.)
1.1.3.
debug(...
data
Perform
Logger
("debug",
data
).
1.1.4.
error(...
data
Perform
Logger
("error",
data
).
1.1.5.
info(...
data
Perform
Logger
("info",
data
).
1.1.6.
log(...
data
Perform
Logger
("log",
data
).
1.1.7.
table(
tabularData
properties
Try to construct a table with the columns of the properties of
tabularData
(or use
properties
) and rows of
tabularData
and log it with a logLevel of "log". Fall
back to just logging the argument if it can’t be parsed as tabular.
TODO: This will need a good algorithm.
1.1.8.
trace(...
data
Let
trace
be some
implementation-defined
, potentially-interactive representation of the
callstack from where this function was called.
Optionally, let
formattedData
be the result of
Formatter
data
), and
incorporate
formattedData
as a label for
trace
Perform
Printer
("trace", «
trace
»).
The identifier of a function printed in a stack trace is
implementation-defined
. It is also
not guaranteed to be the same identifier that would be seen in
new Error().stack
1.1.9.
warn(...
data
Perform
Logger
("warn",
data
).
1.1.10.
dir(
item
options
Let
object
be
item
with
generic JavaScript object formatting
applied.
Perform
Printer
("dir", «
object
»,
options
).
1.1.11.
dirxml(...
data
Let
finalList
be a new
list
, initially empty.
For each
item
of
data
Let
converted
be a DOM tree representation of
item
if possible; otherwise let
converted
be
item
with
optimally useful formatting
applied.
Append
converted
to
finalList
Perform
Logger
("dirxml",
finalList
).
1.2.
Counting functions
Each
console
namespace object has an associated
count map
, which is a
map
of
strings
to numbers, initially empty.
1.2.1.
count(
label
Let
map
be the associated
count map
If
map
label
exists
set
map
label
] to
map
label
] + 1.
Otherwise,
set
map
label
] to 1.
Let
concat
be the concatenation of
label
, U+003A (:), U+0020 SPACE, and
ToString
map
label
]).
Perform
Logger
("count", «
concat
»).
1.2.2.
countReset(
label
Let
map
be the associated
count map
If
map
label
exists
set
map
label
] to 0.
Otherwise:
Let
message
be a string without any formatting specifiers indicating generically that the
given label does not have an associated count.
Perform
Logger
("countReset", «
message
»);
1.3.
Grouping functions
group
is an
implementation-defined
, potentially-interactive
view for output produced by calls to
Printer
, with one further level of
indentation than its parent. Each
console
namespace object has an associated
group
stack
, which is a
stack
, initially empty. Only the last
group
in a
group
stack
will host output produced by calls to
Printer
1.3.1.
group(...
data
Let
group
be a new
group
If
data
is not
empty
, let
groupLabel
be the result of
Formatter
data
). Otherwise, let
groupLabel
be an implementation-chosen
label representing a
group
Incorporate
groupLabel
as a label for
group
Optionally, if the environment supports interactive groups,
group
should be expanded by
default.
Perform
Printer
("group", «
group
»).
Push
group
onto the appropriate
group stack
1.3.2.
groupCollapsed(...
data
Let
group
be a new
group
If
data
is not empty, let
groupLabel
be the result of
Formatter
data
). Otherwise, let
groupLabel
be an implementation-chosen
label representing a
group
Incorporate
groupLabel
as a label for
group
Optionally, if the environment supports interactive groups,
group
should be collapsed by
default.
Perform
Printer
("groupCollapsed", «
group
»).
Push
group
onto the appropriate
group stack
1.3.3.
groupEnd()
Pop
the last
group
from the
group stack
1.4.
Timing functions
Each
console
namespace object has an associated
timer table
, which is a
map
of
strings
to times, initially empty.
1.4.1.
time(
label
If the associated
timer table
contains
an entry with key
label
, return,
optionally reporting a warning to the console indicating that a timer with label
label
has
already been started.
Otherwise,
set
the value of the entry with key
label
in the associated
timer table
to the current time.
1.4.2.
timeLog(
label
, ...
data
Let
timerTable
be the associated
timer table
Let
startTime
be
timerTable
label
].
Let
duration
be a string representing the difference between the current time and
startTime
, in an
implementation-defined
format.
"4650", "4650.69 ms", "5 seconds", and "00:05"
are all reasonable ways of displaying a 4650.69 ms duration.
Let
concat
be the concatenation of
label
, U+003A (:), U+0020 SPACE, and
duration
Prepend
concat
to
data
Perform
Printer
("timeLog", data).
The
data
parameter in calls to
timeLog()
is included in the call to
Logger
to make it easier for users to supply intermediate timer logs with
some extra data throughout the life of a timer. For example:
console
time
"MyTimer"
);
console
timeLog
"MyTimer"
"Starting application up…"
);
// Perhaps some code runs to bootstrap a complex app
// ...
console
timeLog
"MyTimer"
"UI is setup, making API calls now"
);
// Perhaps some fetch()'s here filling the app with data
// ...
console
timeEnd
"MyTimer"
);
1.4.3.
timeEnd(
label
Let
timerTable
be the associated
timer table
Let
startTime
be
timerTable
label
].
Remove
timerTable
label
].
Let
duration
be a string representing the difference between the current time and
startTime
, in an
implementation-defined
format.
Let
concat
be the concatenation of
label
, U+003A (:), U+0020 SPACE, and
duration
Perform
Printer
("timeEnd", «
concat
»).
See
whatwg/console#134
for plans to make
timeEnd()
and
timeLog()
formally report warnings to the
console when a given
label
does not exist in the associated
timer table
2.
Supporting abstract operations
2.1.
Logger(
logLevel
args
The logger operation accepts a log level and a
list
of other arguments. Its main output is the
implementation-defined
side effect of printing the result to the console. This specification
describes how it processes format specifiers while doing so.
If
args
is
empty
, return.
Let
first
be
args
[0].
Let
rest
be all elements following
first
in
args
If
rest
is
empty
, perform
Printer
logLevel
, «
first
») and return.
Otherwise, perform
Printer
logLevel
Formatter
args
)).
Return
undefined
It’s important that the printing occurs before returning from the algorithm. Many developer
consoles print the result of the last operation entered into them. In such consoles, when a
developer enters
console.log("hello!")
, this will first print "hello!", then the
undefined return value from the console.log call.
2.2.
Formatter(
args
The formatter operation tries to format the first argument provided, using the other arguments. It
will try to format the input until no formatting specifiers are left in the first argument, or no
more arguments are left. It returns a
list
of objects suitable for printing.
If
args
’s
size
is 1, return
args
Let
target
be the first element of
args
Let
current
be the second element of
args
Find the first possible format specifier
specifier
, from the left to the right in
target
If no format specifier was found, return
args
Otherwise:
If
specifier
is
%s
, let
converted
be the result of
Call
%String%
undefined
, «
current
»).
If
specifier
is
%d
or
%i
If
current
is a Symbol
, let
converted
be
NaN
Otherwise, let
converted
be the result of
Call
%parseInt%
undefined
, «
current
, 10 »).
If
specifier
is
%f
If
current
is a Symbol
, let
converted
be
NaN
Otherwise, let
converted
be the result of
Call
%parseFloat%
undefined
, «
current
»).
If
specifier
is
%o
, optionally let
converted
be
current
with
optimally useful formatting
applied.
If
specifier
is
%O
, optionally let
converted
be
current
with
generic JavaScript object formatting
applied.
TODO: process %c
If any of the previous steps set
converted
, replace
specifier
in
target
with
converted
Let
result
be a
list
containing
target
together with the elements of
args
starting
from the third onward.
Return
Formatter
result
).
2.2.1.
Summary of formatting specifiers
The following is an informative summary of the format specifiers processed by the above algorithm.
Specifier
Purpose
Type Conversion
%s
Element which substitutes is converted to a string
%String%
element
%d
or
%i
Element which substitutes is converted to an integer
%parseInt%
element
, 10)
%f
Element which substitutes is converted to a float
%parseFloat%
element
, 10)
%o
Element is displayed with
optimally useful formatting
n/a
%O
Element is displayed with
generic JavaScript object formatting
n/a
%c
Applies provided CSS
n/a
2.3.
Printer(
logLevel
args
[,
options
])
The printer operation is
implementation-defined
. It accepts a log level indicating severity,
a List of arguments to print, and an optional object of implementation-specific formatting options.
Elements appearing in
args
will be one of the following:
JavaScript objects of any type.
Implementation-specific representations of printable things such as a stack trace or
group
Objects with either
generic JavaScript object formatting
or
optimally useful formatting
applied.
If the
options
object is passed, and is not undefined or null, implementations may use
options
to apply
implementation-defined
formatting to the elements in
args
How the implementation prints
args
is up to the implementation, but implementations should
separate the objects by a space or something similar, as that has become a developer expectation.
By the time the printer operation is called, all format specifiers will have been taken into
account, and any arguments that are meant to be consumed by format specifiers will not be present in
args
. The implementation’s job is simply to print the List. The output produced by calls to
Printer should appear only within the last
group
on the appropriate
group stack
if the
group stack
is not empty, or elsewhere in the console otherwise.
If the console is not open when the printer operation is called, implementations should buffer
messages to show them in the future up to an
implementation-defined
limit (typically on the
order of at least 100).
2.3.1.
Indicating
logLevel
severity
Each
console
function uses a unique value for the
logLevel
parameter when calling
Printer, allowing implementations to customize each printed message depending on the function from
which it originated. However, it is common practice to group together certain functions and treat
their output similarly, in four broad categories. This table summarizes these common groupings:
Grouping
console
functions
Description
log
log()
trace()
dir()
dirxml()
group()
groupCollapsed()
debug()
timeLog()
A generic log
info
count()
info()
timeEnd()
An informative log
warn
warn()
countReset()
A log warning the user of something indicated by the message
error
error()
assert()
A log indicating an error to the user
These groupings are meant to document common practices, and do not constrain implementations from
providing special behavior for each function, as in the following examples:
Here you can see one implementation chose to make output produced by calls to
timeEnd()
blue, while leaving
info()
a more neutral color.
Calls to
count()
might not always print new output, but instead could update
previously-output counts.
2.3.2.
Printer user experience innovation
Since
Printer
is
implementation-defined
, it is common to see UX
innovations in its implementations. The following is a non-exhaustive list of potential UX
enhancements:
De-duplication of identical output to prevent spam.
In this example, the implementation not only batches multiple identical messages, but also
provides the number of messages that have been batched together.
Extra UI off to the side allowing the user to filter messages by log level severity.
Extra UI off to the side indicating the current state of the
timer table
group stack
, or other internally maintained data.
Flashing portions of the console to alert the user of something important.
2.3.3.
Common object formats
Typically objects will be printed in a format that is suitable for their context. This section
describes common ways in which objects are formatted to be most useful in their context. It should
be noted that the formatting described in this section is applied to
implementation-defined
object representations that will eventually be passed into
Printer
, where the
actual side effect of formatting will be seen.
An object with
generic JavaScript object formatting
is a potentially expandable
representation of a generic JavaScript object. An object with
optimally useful formatting
is an
implementation-defined
, potentially-interactive
representation of an object judged to be maximally useful and informative.
2.3.4.
Example printer in Node.js
The simplest way to implement the printer operation on the Node.js platform is to join the
previously formatted arguments separated by a space and write the output to
stdout
or
stderr
Example implementation in Node.js using
[ECMASCRIPT]
const
util
require
'util'
);
function
logLevel
...
args
const
message
util
format
(...
args
);
if
logLevel
===
'error'
process
stderr
write
message
'\n'
);
else
if
logLevel
===
'log'
||
logLevel
===
'info'
||
logLevel
===
'warn'
process
stdout
write
message
'\n'
);
Here a lot of the work is done by the
util.format
function. It stringifies nested objects, and
converts non-string arguments into a readable string version, e.g. undefined becomes the string
"undefined" and false becomes "false":
'log'
'duck'
[{
foo
'bar'
}]);
// prints:
duck
foo
'bar'
\n
on stdout
'log'
'duck'
false
);
// prints:
duck
false
\n
on stdout
'log'
'duck'
undefined
);
// prints:
duck
undefined
\n
on stdout
2.4.
Reporting warnings to the console
To
report a warning to the console
given a generic description of a warning
description
, implementations must run these steps:
Let
warning
be an
implementation-defined
string derived from
description
Perform
Printer
("reportWarning", «
warning
»).
Acknowledgments
The editors would like to thank
Boris Zbarsky,
Brent S.A. Cowgill,
Brian Grinstead,
Corey Farwell,
Ian Kilpatrick,
Jeff Carpenter,
Joseph Pecoraro,
Justin Woo,
Luc Martin,
Noah Bass,
Paul Irish,
Raphaël, and
Victor Costan
for their contributions to this specification. You are awesome!
This standard is written by
Terin Stock
terin@terinstock.com
),
Robert Kowalski
rok@kowalski.gd
), and
Dominic Farolino
domfarolino@gmail.com
with major help from
Domenic Denicola
Google
d@domenic.me
).
Intellectual property rights
Copyright © WHATWG (Apple, Google, Mozilla, Microsoft). This work is licensed under a
Creative Commons Attribution 4.0
International License
. To the extent portions of it are incorporated into source code, such
portions in the source code are licensed under the
BSD 3-Clause License
instead.
This is the Living Standard. Those
interested in the patent-review version should view the
Living Standard Review Draft
Index
Terms defined by this specification
assert()
, in § 1.1
assert(condition)
, in § 1.1
assert(condition, ...data)
, in § 1.1
clear()
, in § 1.1.1
console
, in § 1
count()
, in § 1.2
count(label)
, in § 1.2
count map
, in § 1.2
countReset()
, in § 1.2.1
countReset(label)
, in § 1.2.1
debug()
, in § 1.1.2
debug(...data)
, in § 1.1.2
dir()
, in § 1.1.9
dir(item)
, in § 1.1.9
dir(item, options)
, in § 1.1.9
dirxml()
, in § 1.1.10
dirxml(...data)
, in § 1.1.10
error()
, in § 1.1.3
error(...data)
, in § 1.1.3
Formatter
, in § 2.1
generic JavaScript object formatting
, in § 2.3.3
group
, in § 1.3
group()
, in § 1.3
groupCollapsed()
, in § 1.3.1
groupCollapsed(...data)
, in § 1.3.1
group(...data)
, in § 1.3
groupEnd()
, in § 1.3.2
group stack
, in § 1.3
info()
, in § 1.1.4
info(...data)
, in § 1.1.4
log()
, in § 1.1.5
log(...data)
, in § 1.1.5
Logger
, in § 2
optimally useful formatting
, in § 2.3.3
Printer
, in § 2.2.1
report a warning to the console
, in § 2.4
table()
, in § 1.1.6
table(tabularData)
, in § 1.1.6
table(tabularData, properties)
, in § 1.1.6
time()
, in § 1.4
timeEnd()
, in § 1.4.2
timeEnd(label)
, in § 1.4.2
time(label)
, in § 1.4
timeLog()
, in § 1.4.1
timeLog(label)
, in § 1.4.1
timeLog(label, ...data)
, in § 1.4.1
timer table
, in § 1.4
trace()
, in § 1.1.7
trace(...data)
, in § 1.1.7
warn()
, in § 1.1.8
warn(...data)
, in § 1.1.8
Terms defined by reference
[ECMASCRIPT]
defines the following terms:
%ObjectPrototype%
%String%
%parseFloat%
%parseInt%
Call
ObjectCreate
ToString
is a Symbol
is not a String
[INFRA]
defines the following terms:
append
contain
empty
exist
for each
implementation-defined
is empty
list
map
pop
prepend
push
remove
set
size
stack
string
[WEBIDL]
defines the following terms:
DOMString
any
boolean
namespace object
object
sequence
undefined
References
Normative References
[ECMASCRIPT]
ECMAScript Language Specification
. URL:
[INFRA]
Anne van Kesteren; Domenic Denicola.
Infra Standard
. Living Standard. URL:
[WEBIDL]
Edgar Chen; Timothy Gu.
Web IDL Standard
. Living Standard. URL:
IDL Index
[Exposed=*]
namespace
console
{ // but see namespace object requirements below
// Logging
undefined
assert
optional
boolean
condition
false
any
...
data
);
undefined
clear
();
undefined
debug
any
...
data
);
undefined
error
any
...
data
);
undefined
info
any
...
data
);
undefined
log
any
...
data
);
undefined
table
optional
any
tabularData
optional
sequence
DOMString
properties
);
undefined
trace
any
...
data
);
undefined
warn
any
...
data
);
undefined
dir
optional
any
item
optional
object
options
);
undefined
dirxml
any
...
data
);
// Counting
undefined
count
optional
DOMString
label
= "default");
undefined
countReset
optional
DOMString
label
= "default");
// Grouping
undefined
group
any
...
data
);
undefined
groupCollapsed
any
...
data
);
undefined
groupEnd
();
// Timing
undefined
time
optional
DOMString
label
= "default");
undefined
timeLog
optional
DOMString
label
= "default",
any
...
data
);
undefined
timeEnd
optional
DOMString
label
= "default");
};
MDN
console/assert
In all current engines.
Firefox
28+
Safari
4+
Chrome
2+
Opera
11+
Edge
79+
Edge (Legacy)
12+
IE
8+
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
11+
Node.js
10.0.0+
MDN
console/clear
In all current engines.
Firefox
39+
Safari
7+
Chrome
25+
Opera
12+
Edge
79+
Edge (Legacy)
12+
IE
8+
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
12+
Node.js
8.3.0+
MDN
console/count
In all current engines.
Firefox
30+
Safari
4+
Chrome
2+
Opera
11+
Edge
79+
Edge (Legacy)
12+
IE
11
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
11+
Node.js
8.3.0+
MDN
console/countReset
In all current engines.
Firefox
62+
Safari
13+
Chrome
68+
Opera
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
Node.js
8.3.0+
MDN
console/debug
In all current engines.
Firefox
5+
Safari
4+
Chrome
2+
Opera
11+
Edge
79+
Edge (Legacy)
12+
IE
10+
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
11+
Node.js
8.0.0+
MDN
console/dir
In all current engines.
Firefox
8+
Safari
4+
Chrome
2+
Opera
11+
Edge
79+
Edge (Legacy)
12+
IE
9+
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
11+
Node.js
0.10.0+
MDN
console/dirxml
In all current engines.
Firefox
39+
Safari
4+
Chrome
2+
Opera
11+
Edge
79+
Edge (Legacy)
12+
IE
11
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
11+
Node.js
9.3.0+
MDN
console/error
In all current engines.
Firefox
4+
Safari
3+
Chrome
1+
Opera
10.5+
Edge
79+
Edge (Legacy)
12+
IE
8+
Firefox for Android
iOS Safari
1+
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
11+
Node.js
0.10.0+
MDN
console/group
In all current engines.
Firefox
9+
Safari
4+
Chrome
2+
Opera
11+
Edge
79+
Edge (Legacy)
12+
IE
11
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
11+
Node.js
8.5.0+
MDN
console/groupCollapsed
In all current engines.
Firefox
9+
Safari
5.1+
Chrome
6+
Opera
11+
Edge
79+
Edge (Legacy)
12+
IE
11
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
3+
Samsung Internet
Opera Mobile
11+
Node.js
8.5.0+
MDN
console/groupEnd
In all current engines.
Firefox
9+
Safari
4+
Chrome
2+
Opera
11+
Edge
79+
Edge (Legacy)
12+
IE
11
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
11+
Node.js
8.5.0+
MDN
console/info
In all current engines.
Firefox
4+
Safari
3+
Chrome
1+
Opera
10.5+
Edge
79+
Edge (Legacy)
12+
IE
8+
Firefox for Android
iOS Safari
1+
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
11+
Node.js
0.10.0+
MDN
console/log
In all current engines.
Firefox
4+
Safari
3+
Chrome
1+
Opera
10.5+
Edge
79+
Edge (Legacy)
12+
IE
8+
Firefox for Android
iOS Safari
1+
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
11+
Node.js
0.10.0+
MDN
console/table
In all current engines.
Firefox
34+
Safari
7+
Chrome
27+
Opera
11+
Edge
79+
Edge (Legacy)
13+
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
11+
Node.js
10.0.0+
MDN
console/time
In all current engines.
Firefox
10+
Safari
4+
Chrome
2+
Opera
11+
Edge
79+
Edge (Legacy)
12+
IE
11
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
11+
Node.js
0.10.0+
MDN
console/timeEnd
In all current engines.
Firefox
10+
Safari
4+
Chrome
2+
Opera
11+
Edge
79+
Edge (Legacy)
12+
IE
11
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
11+
Node.js
0.10.0+
MDN
console/timeLog
In all current engines.
Firefox
62+
Safari
13+
Chrome
71+
Opera
60+
Edge
79+
Edge (Legacy)
IE
None
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
Node.js
10.7.0+
MDN
console/trace
In all current engines.
Firefox
6+
Safari
4+
Chrome
2+
Opera
11+
Edge
79+
Edge (Legacy)
12+
IE
11
Firefox for Android
iOS Safari
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
11+
Node.js
0.10.0+
MDN
console/warn
In all current engines.
Firefox
4+
Safari
3+
Chrome
1+
Opera
10.5+
Edge
79+
Edge (Legacy)
12+
IE
8+
Firefox for Android
iOS Safari
1+
Chrome for Android
Android WebView
Samsung Internet
Opera Mobile
11+
Node.js
0.10.0+
MDN
console
In all current engines.
Firefox
4+
Safari
3+
Chrome
1+
Opera
10.5+
Edge
79+
Edge (Legacy)
12+
IE
8+
Firefox for Android
iOS Safari
1+
Chrome for Android
Android WebView
37+
Samsung Internet
Opera Mobile
11+
Node.js
0.10.0+