Nullish coalescing operator in object not working but ternary does

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I have an object that has a selector property which should receive a function callback:

{
  selector: (element) => element.name
}

but I want to conditionally pick another callback function for the selector via the ?? operator from another object:

const extendedCallback = {
  example: (element) => element.another
}

so what I do is:

{
  selector: extendedCallback.example ?? (element) => element.name
}

but then my IDE says Cannot find name 'element'.ts(2304) for the right handed side of the operator. When I do the same with ternary:

'example' in extendedCallback ? extendedCallback.example : (element) => element.name

it works fine. What is a misconception I have about the ?? ?

javascript
1 Answers

Your problem is operator precedence, => has lower precedence than ?? so your code gets interpreted as

(extendedCallback.example ?? (element)) => element.name

You need to use parentheses to get the correct operation.

selector: extendedCallback.example ?? ((element) => element.name)
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