Repository navigation
Error when attempting to inline destructure rest parameters #29404
Description
TypeScript Version: 3.3.0-dev.201xxxxx
Search Terms: rest parameters inline type destructure error
Code
function foo(...[a, b]) {
return a + b;
}Expected behavior:
The code is valid JavaScript and should compile without errors.
Actual behavior:
It errors:
index.ts:1:17 - error TS2501: A rest element cannot contain a binding pattern.
Why would you want to destructure rest params like this? In order to use Parameters<T> to type the parameters based on another function:
function foo(a: string, b: number) {}
function bar(...[a, b]: Parameters<typeof foo>) {}Playground Link: https://www.typescriptlang.org/play/index.html#src=function%20foo(...%5Ba%2C%20b%5D)%20%7B%0D%0A%20%20%20%20return%20a%20%2B%20b%3B%0D%0A%7D%0D%0A
Related Issues:
Reacted by Ruslan Fadeev
Activity
Kinrany commentedon Jan 14, 2019
Would this work?
jonrimmer commentedon Jan 14, 2019
Ruslan Fadeev (@Kinrany) Yes, I think so. There are a few other workarounds. But none are as succinct, and given that it's valid JS, and TS is supposed to be a superset, I think this construction should work.
weswigham commentedon Jan 14, 2019
Duplicate of #6275, #26017 is already up.
typescript-bot commentedon Jan 17, 2019
This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.