sindresorhus/type-fest

Proposal: `ValueOfDeep<Type, 'key.deepKey'>`

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#822 opened on Mar 1, 2024

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 (2 comments) (5 reactions) (0 assignees)TypeScript (12,328 stars) (471 forks)batch import
component:pathshelp wantedtype addition

Description

Short summary

Given: Type: Any type

Provide: Create a type based on the ValueOf of a deeply nested property.

Potential definition

type ValueOfDeep<Type, PathUnion extends Paths<T>>

Use case

Selecting deeply nested objects to be the value of a new type. This may be relevant for auto-generated types where the deep objects aren't unique types but are used independently on the application.

Contributor guide

Tech stack
typescript
Domain
developer experiencetooling
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
TypeScriptunderstanding of conditional types
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60
Research direction
Review existing utility types in type fest such as ValueOf and Paths to understand the pattern. The proposal suggests creating a type that extracts deeply nested property values given a dot separated path. Check discussions in issue comments for any design decisions. Implement ValueOfDeep<Type, Path> using recursive conditional types similar to existing deep types in the library.