Type 'undefined' is not assignable to type 'xxx' with if else on parameter

Asked Aug 18 '20 at 22:30

Active Aug 18 '20 at 22:30

Viewed 378 times

anyone know how I can fix the following? I will have the error from vscode/webstorm Type 'undefined' is not assignable to type 'string' I have one customize function only accept one parameter with string type and I using if/else to filter out the parameter from undefined or string, but I still get the error Type 'undefined' is not assignable to type 'string' what is the best way for me to fix it?

function abc(value: string | number) {
    console.log(value)
}

abc(typeof x !== 'undefined' ? x : 'dummy string')
abc(0) // 0
abc(1) // 1
abc('') // ''

asked Aug 18 '20 at 22:30

jacobcan118

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How is `x` declared? – Ryan Cavanaugh Aug 18 '20 at 22:32
I think [this answer](https://stackoverflow.com/a/45195136/2299362) is what you're looking for. You're declaring an explicit type for `value`, and `undefined` is not part of those types. – Pipetus Aug 18 '20 at 22:34
@Taplar that is my main question, I should not affect 0 – jacobcan118 Aug 18 '20 at 22:39
https://jsfiddle.net/hu3scnwr/ I'm not seeing that error replicated. – Taplar Aug 18 '20 at 22:41
1

There isn't an if / else in your code example, so I'm guessing you've written a simpler snippet to explain the problem you're having. Unfortunately the simpler snippet does not replicate the issue. – Charlie Bamford Aug 18 '20 at 22:52

Type 'undefined' is not assignable to type 'xxx' with if else on parameter

0 Answers0