Console.warn()

Outputs a warning message to the Web Console.

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.

• MSDN: Using the F12 Tools Console to View Errors and Status