Argument of type 'number | undefined' is not assignable to parameter of type 'number'.

How fix this?

10 Replies

Jochem•2y ago

add a default values with ?? 0 at the end, or redefine the signature for convertToMinuteSeconds to deal with undefined

NikitaOP•2y ago

Jochem•2y ago

please paste your code in acode block instead of sharing screenshots I'm not typing everything out, but I can show you where to put it if I can copy-paste it

NikitaOP•2y ago

 const onTimeUpdate = () => {
    setCurrentTime(() => convertToMinuteSeconds(videoRef.current ??.currentTime))
  }

 const onTimeUpdate = () => {
    setCurrentTime(() => convertToMinuteSeconds(videoRef.current ??.currentTime))
  }

Jochem•2y ago

 const onTimeUpdate = () => {
    setCurrentTime(() => convertToMinuteSeconds(videoRef.current?.currentTime ?? 0))
  }

 const onTimeUpdate = () => {
    setCurrentTime(() => convertToMinuteSeconds(videoRef.current?.currentTime ?? 0))
  }

NikitaOP•2y ago

Thank you

Jochem•2y ago

?? is called the nullish coalescing operator, it returns the first value if it's not nullish (so null or undefined), and the second value if the first one is nullish https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Nullish_coalescing

Queequeg•2y ago

@jochemm I was going to suggest using a logical OR like so:

 const onTimeUpdate = () => {
    setCurrentTime(() => convertToMinuteSeconds(videoRef.current?.currentTime || 0))
  }

 const onTimeUpdate = () => {
    setCurrentTime(() => convertToMinuteSeconds(videoRef.current?.currentTime || 0))
  }

Do you think the ?? operator better or about the same as || in situations like these? Given, of course, that a 0 will fall through to default as 0 in this case. I have not used ?? in code before, I have used || a ton.

Jochem•2y ago

|| coerces the left hand side to boolean, which means you're checking for falseish instead of nullish the string '0', empty string, NaN, all convert to false the error in this case is saying that the value of the expression is either undefined or a number, so it's going to narrow down to what you said, 0 falling through to the default, but in general I prefer using ?? because it's narrower and more explicit when you're reading the code

Queequeg•2y ago

I learn something new every day! Thanks. While reading the documentation, I also learned that combining || and ?? in a series of checks will not work without parenthesis. This is something to keep in mind as I frequently do this too.

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Argument of type 'number | undefined' is not assignable to parameter of type 'number'.