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console.warn

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.

console.warn(obj1 [, obj2, ..., objN]);
console.warn(msg [, subst1, ..., substN]);

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.

Specification	Status	Comment
Console API The definition of 'console.warn()' in that specification.	Living Standard	Initial definition

	Desktop
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic support	Yes	12	4	8	Yes	Yes
Substitution strings	Yes	Yes	9	10 10 %c is not supported, %d will render as 0 when it is not a number	?	?