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Intellisense doesn't show type info about array index access on hover #59696
Description
🔍 Search Terms
intellisense, array, array index access, array square bracket access, hover
✅ Viability Checklist
- This wouldn't be a breaking change in existing TypeScript/JavaScript code
- This wouldn't change the runtime behavior of existing JavaScript code
- This could be implemented without emitting different JS based on the types of the expressions
- This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, new syntax sugar for JS, etc.)
- This isn't a request to add a new utility type: https://github.com/microsoft/TypeScript/wiki/No-New-Utility-Types
- This feature would agree with the rest of our Design Goals: https://github.com/Microsoft/TypeScript/wiki/TypeScript-Design-Goals
⭐ Suggestion
Array index access, e.g. arr[0], to show type info when hovering over the index.
📃 Motivating Example
const arr = [0, 1]
arr[0] // 💥 no hover. Expected "(property) 0: number" or "(property) 0?: number | undefined" with `noUncheckedIndexedAccess`
arr['1'] // 💥 no hover. Expected "(property) 1: number" or "(property) 1?: number | undefined" with `noUncheckedIndexedAccess`
arr['0'] // 💥 no hover. Expected "(property) 0: number" or "(property) 0?: number | undefined" with `noUncheckedIndexedAccess`
arr[1] // 💥 no hover. Expected "(property) 1: number" or "(property) 1?: number | undefined" with `noUncheckedIndexedAccess`
arr[2] // 💥 no hover. Expected "(property) 2: number" or "(property) 2?: number | undefined" with `noUncheckedIndexedAccess`
// for comparison
const obj = { 0: 0, '1': 1, key: 2 }
const tuple = [0, 1] as const
const extendedArr = Object.assign([0, 1] , { key: 2 })
obj.key // ✅ ok
obj['key'] // ✅ ok
obj[0] // ✅ ok
obj['1'] // ✅ ok
obj['0'] // ✅ ok
obj[1] // ✅ ok
tuple[0] // ✅ ok
tuple['1'] // ✅ ok
tuple['0'] // ✅ ok
tuple[1] // ✅ ok
tuple[2] // ✅ ok (fails type check as expected)
extendedArr.key // ✅ ok
extendedArr['key'] // ✅ ok
extendedArr[0] // 💥 no hover
extendedArr['1'] // 💥 no hover
extendedArr['0'] // 💥 no hover
extendedArr[1] // 💥 no hover💻 Use Cases
- What do you want to use this for?
- DX/quality of life improvement
- What shortcomings exist with current approaches?
- Less good DX
- What workarounds are you using in the meantime?
- N/A
Activity
jcalz commentedon Aug 20, 2024
Looks like #58908
typescript-bot commentedon Aug 23, 2024
This issue has been marked as "Duplicate" and has seen no recent activity. It has been automatically closed for house-keeping purposes.