Outputs a warning message to the Web Console.

Note: This feature is available in Web Workers.
Note: In Firefox, warnings have a small exclamation point icon next to them in the Web Console log.

Syntax

console.warn(obj1 [, obj2, ..., objN]);
console.warn(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.warn()' in that specification.
Living Standard Initial definition

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung Internet
Basic supportChrome Full support YesEdge Full support 12Firefox Full support 4IE Full support 8Opera Full support YesSafari Full support YesWebView Android ? Chrome Android ? Edge Mobile Full support YesFirefox Android Full support 4Opera Android ? Safari iOS ? Samsung Internet Android ?
Substitution stringsChrome Full support YesEdge Full support YesFirefox Full support 9IE Full support 10
Notes
Full support 10
Notes
Notes %c is not supported, %d will render as 0 when it is not a number
Opera ? Safari ? WebView Android ? Chrome Android ? Edge Mobile Full support YesFirefox Android Full support 9Opera Android ? Safari iOS ? Samsung Internet Android ?

Legend

Full support  
Full support
Compatibility unknown  
Compatibility unknown
See implementation notes.
See implementation notes.

See also

Document Tags and Contributors

Last updated by: ExE-Boss,