console.warn()

The console.warn() method outputs a warning message to the Web console.

Note: This feature is available in Web Workers

Note: In Chrome and 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]);

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
Console Standard (Console) # warn

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`warn`	1	12	4	8	10.5	3	1	18	4	11	1	1.0
`substitution_strings`	1	12 ["Before Edge 79, `%c` is not supported.", "Before Edge 79, `%d` outputs a 0 if the specified value isn't a number."]	9	10 ["`%c` is not supported.", "`%d` outputs a 0 if the specified value isn't a number."]	15	3	1	18	9	14	1	1.0