ts-deep-types

A comprehensive collection of type-safe utility types for TypeScript.

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What It Does

Provides missing TypeScript utility types that should exist in the standard library but don't:

• Deep types — Recursive transformations on nested objects
• String types — Case conversion (camelCase, snake_case, kebab-case)
• Function types — Parameter/return type extraction
• Type guards — Runtime type checking
• Object utilities — Key/value manipulation

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Installation

# npm
npm install ts-deep-types

# pnpm
pnpm add ts-deep-types

# yarn
yarn add ts-deep-types

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Usage

import { DeepPartial, CamelCase, Parameters, IsAny } from 'ts-deep-types'

// Deep types
type PartialConfig = DeepPartial<{
  database: { host: string; port: number }
}>
// { database?: { host?: string; port?: number } | undefined }

// String types
type CamelStr = CamelCase<'hello_world'>
// 'helloWorld'

// Function types
type FnParams = Parameters<(a: string, b: number) => void>
// [string, number]

// Type guards
type TestAny = IsAny<any>      // true
type TestNever = IsAny<never>   // false

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Features

Core Types

• DeepPartial - Recursive partial types
• DeepRequired - Recursive required types
• DeepReadonly - Deep readonly for nested objects
• PickDeep - Deep pick with nested paths
• OmitDeep - Deep omit with nested paths
• Merge - Merge two object types
• UnionToIntersection - Convert union to intersection

String Types

• CamelCase - Convert to camelCase
• KebabCase - Convert to kebab-case
• SnakeCase - Convert to snake_case
• PascalCase - Convert to PascalCase
• Trim - Trim strings in templates

Function Types

• Parameters - Function parameters
• ReturnType - Return type
• ThisParameterType - this parameter type
• AsyncReturnType - Async version of ReturnType

Type Guards

• IsAny - Check if type is any
• IsNever - Check if type is never
• IsUnknown - Check if type is unknown
• IsUnion - Check if type is a union
• IsTuple - Check if type is a tuple
• IsArray - Check if type is an array
• IsPlainObject - Check if type is a plain object
• IsFunction - Check if type is a function
• IsConstructor - Check if type is a constructor

Object Utilities

• KeysOfType - Keys matching a type
• ValueOf - Values of a union type
• EntryOf - Key-value entries
• RequiredKeys - Keys that are required
• OptionalKeys - Keys that are optional
• ReadonlyKeys - Keys that are readonly
• WritableKeys - Keys that are mutable

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Why ts-deep-types?

TypeScript's standard utility types (Partial, Pick, Omit) only work at one level. When you need recursive transformations, you're on your own.

ts-deep-types provides the missing utilities:

// Standard library (one level)
type A = Partial<{ a: { b: { c: string } } }>
// { a?: { b?: { c?: string } } | undefined } | undefined

// ts-deep-types (recursive)
type B = DeepPartial<{ a: { b: { c: string } } }>
// { a?: { b?: { c?: string } } | undefined } | undefined }
// All levels are partial!

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Development

# Install dependencies
pnpm install

# Run tests
pnpm test

# Build for production
pnpm build

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License

MIT © Peter W.

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Contributing

Issues and PRs welcome!