JS colon syntax outside of an object literal?

Question

I'm seeing the below function as an example of the babel plugin. What is the pre: doing in this function? I've tried with and without it and the result is the same.

function warn (message) {
  pre: typeof message === 'string';
  return 'Warning!\n' + message;
}

edit: Babel plugin

I think it depends on how the babel plugin works. Do you have a link to it? Looks like it could be some kind of type checking. — Cory Danielson
– Cory Danielson, Commented Dec 9, 2015 at 22:33

Quentin · Accepted Answer · 2015-12-09 22:34:24Z

7

It is a label (a type of GOTO primerily used to manipulate loops (e.g. with continue) when dealing with nested loops).

In that particular case, it is not doing anything practical since there is no loop and nothing references it.

answered Dec 9, 2015 at 22:34

Quentin

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