void before promise syntax

Question

What is the actual impact of putting void before promise?

async function doAsyncStuff(){
...
}

function nonAsyncFunction(){
  void doAsyncStuff();
}

I couldn't find any official documentation for this, but it must be doing something as it resolves no-floating-promises TSLint error.

Outstrip

how about documentation for the void operator? developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… – Sutphin

Yep, that's exactly what I was looking for. Tried to find it in Promise docs, apparently I wasn't looking in the right place. – Outstrip

yeah, void has been a javascript operator since Brendan Eich wore short pants :p – Sutphin

See also: Can I fire and forget a promise in nodejs (ES7)? – Cromagnon

I personally prefer /*await*/ fireAndForget(); cause that is also understood by people that aren't that familiar with JS, it doesn't stop the linter from complaining though – Shill

Answer 1

void is an operator that accepts a value on the Right-Hand Side and evaluates as undefined.

It resolves no-floating-promises because it does something (or rather, explicitly nothing) with the promise.

Doloritas

Oh wow, TIL people were using void to suppress the rule. Filed github.com/palantir/tslint/issues/4653. Thanks for this @Quentin! – Rockrose

^ or, how to render the answer incorrect in one easy step. – Rhoda

Looks like this behaviour can be had back with some config, at least with typescript-eslint. See typescript-eslint.io/rules/no-floating-promises – Rhoda