node.js - Javascript shorthand for calling a callback function if it is not null?

If we have:

(cb)=>{ if (cb!=null) cb()}

Is there are shorter way to check if cb is not null and call it? This will be running on Node.

If we have:

(cb)=>{ if (cb!=null) cb()}

Is there are shorter way to check if cb is not null and call it? This will be running on Node.

Share Improve this question edited May 8, 2018 at 17:02 asked May 8, 2018 at 14:42 Ole 47k68 gold badges237 silver badges441 bronze badges

10 For the record, good code is not shorter, it's more readable – Sterling Archer Commented May 8, 2018 at 14:44
Agreed, there's nothing wrong with that as it is. – Pointy Commented May 8, 2018 at 14:44
This code's syntax is wrong – Phiter Commented May 8, 2018 at 14:44
3 Just if (cb) cb() should do, but if (typeof cb=="function") cb() would be better. Arguably, don't ever use optional callback parameters anyway… – Bergi Commented May 8, 2018 at 14:45
1 cb?.() - developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… – riv Commented Nov 29, 2020 at 16:36

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2 Answers 2

Sorted by: Reset to default 13

Now in 2021 : Optional chaining

cb?.()

If cb is null - cb is not invoked.

if cb is a func, cb is invoked.

Note: if cb is a not function or a non null/undefined value, (eg 23 or false) then this will throw a TypeError.

You could check cb directly.

In the case where cb is a function, you get a truthy value as first check and then it calls the function.

If cb is null, then the first part is falsy and the second does not get executed.

cb => cb && cb()