Typescript: Array with min length, and more

Created on 19 Apr 2018 · 5Comments · Source: microsoft/TypeScript

TypeScript Version: 2.7.0-dev.201xxxxx

Search Terms:

Code

need something like [string, string, ...argv] or [string, string] & string[]

abc(['', '', ''])

function abc(data: [string, string] & string[]){}

Expected behavior:

allow a array with length >= 2

Actual behavior:

array length only allow 2

Playground Link:

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Question

Source

bluelovers

Most helpful comment

type ArrayTwoOrMore<T> = {
    0: T
    1: T
} & Array<T>

declare function abc(data: ArrayTwoOrMore<string>)

abc([]) // got expected error
abc(["a"]) // got expected error 
abc(["a", "b"]) // no error
abc(["a", "b", "c"]) // no error

Playground link

Edit: Converted to stackoverflow question since I didn't notice any already existing: https://stackoverflow.com/questions/49910889/typescript-array-with-minimum-length

kpdonn on 19 Apr 2018

👍2

All 5 comments

type ArrayTwoOrMore<T> = {
    0: T
    1: T
} & Array<T>

declare function abc(data: ArrayTwoOrMore<string>)

abc([]) // got expected error
abc(["a"]) // got expected error 
abc(["a", "b"]) // no error
abc(["a", "b", "c"]) // no error

Playground link

Edit: Converted to stackoverflow question since I didn't notice any already existing: https://stackoverflow.com/questions/49910889/typescript-array-with-minimum-length

kpdonn on 19 Apr 2018

👍2

@kpdonn thx

bluelovers on 19 Apr 2018

👍1

@kpdonn hmm

there has something happen when i use ...argv

console.log(abc([str, n, s])); // => no error
console.log(abc([str, n, s, ...argv])); // => error

2018-04-21-00-04-46-1

bluelovers on 20 Apr 2018

@bluelovers It looks like spreading argv causes it to see the entire expression as just string[] and lose the information about the earlier indices. It might be worth opening a new issue specifically about that case since it might be considered a bug. Seems like one to me anyway.

kpdonn on 23 Apr 2018

Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.