TypeScript Utility Types Reference

Generate comprehensive, accurate documentation for TypeScript's built-in utility types with practical examples and common use cases.

What This Skill Does

This skill helps you create detailed reference documentation for TypeScript utility types. It covers all built-in utility types including Partial, Required, Pick, Omit, Record, Awaited, Readonly, Exclude, Extract, NonNullable, Parameters, ConstructorParameters, ReturnType, InstanceType, and more.

Instructions

When the user requests TypeScript utility type documentation, follow these steps:

1. **Identify the scope**: Determine which utility types to document (all, or specific ones requested by the user).

2. **Structure the documentation** with the following sections for each utility type:

- **Name and signature**: `UtilityName<Type>`

- **Release version**: TypeScript version when introduced

- **Purpose**: Clear one-sentence description of what it does

- **Syntax**: Type signature and parameters

- **Example code**: At least 2-3 practical examples showing real-world usage

- **Use cases**: When and why to use this utility type

- **Related utilities**: Other utility types that complement or contrast with it

3. **Include comprehensive examples** that demonstrate:

- Basic usage with simple types

- Advanced usage with complex types

- Common patterns (e.g., API response typing, form handling, state management)

- Edge cases and limitations

4. **Format the output** as markdown with:

- Clear headings and hierarchy

- Syntax-highlighted TypeScript code blocks

- Tables for quick reference when appropriate

- Links to official TypeScript documentation

5. **Cover these essential utility types** (unless user specifies otherwise):

- **Partial<Type>**: Make all properties optional

- **Required<Type>**: Make all properties required

- **Readonly<Type>**: Make all properties read-only

- **Pick<Type, Keys>**: Select specific properties

- **Omit<Type, Keys>**: Remove specific properties

- **Record<Keys, Type>**: Create object type with specific keys

- **Exclude<UnionType, ExcludedMembers>**: Remove types from union

- **Extract<Type, Union>**: Extract types from union

- **NonNullable<Type>**: Remove null and undefined

- **Parameters<Type>**: Extract function parameter types

- **ConstructorParameters<Type>**: Extract constructor parameter types

- **ReturnType<Type>**: Extract function return type

- **InstanceType<Type>**: Extract instance type of constructor

- **Awaited<Type>**: Unwrap Promise types

6. **Add practical context** for each utility:

- Compare with alternative approaches

- Show before/after transformations

- Explain common pitfalls

- Provide IDE/editor tips

Example Usage

**User**: "Document TypeScript utility types for working with APIs"

**Expected Output Structure**:

```markdown

TypeScript Utility Types for API Development

Overview

Essential utility types for type-safe API interactions...

Partial<Type>

**Use case**: Patch/update endpoints where only some fields are sent

[code example with API update function]

Pick<Type, Keys>

**Use case**: Selecting specific fields for response DTOs

[code example with API response transformation]

Record<Keys, Type>

**Use case**: Typed API endpoint configurations

[code example with route definitions]

[Continue for each relevant utility...]

```

Notes