AgentSkillsCN

typescript-strict

使用严格模式编写TypeScript时使用——涵盖类型定义、泛型和声明文件

SKILL.md
--- frontmatter
name: typescript-strict
# prettier-ignore
description: Use when writing TypeScript with strict mode - covers type definitions, generics, and declaration files

TypeScript Strict Mode Best Practices

Quick Start

typescript
// Enable strict in tsconfig.json
{
  "compilerOptions": {
    "strict": true,
    "noUncheckedIndexedAccess": true,
    "exactOptionalPropertyTypes": true
  }
}

Core Principles

  • •Strict null checks: Handle undefined and null explicitly
  • •No implicit any: Always declare types, avoid any
  • •Readonly by default: Use readonly for immutable data
  • •Discriminated unions: Use type guards with tagged unions

Type Definition Patterns

AST Node Types

typescript
// Discriminated union for AST nodes
type Expr =
  | { type: "NumberLiteral"; value: number }
  | { type: "BinaryExpr"; op: string; left: Expr; right: Expr }
  | { type: "Identifier"; name: string };

// Type guard
function isNumberLiteral(expr: Expr): expr is Extract<Expr, { type: "NumberLiteral" }> {
  return expr.type === "NumberLiteral";
}

Generic Types

typescript
// Constrained generics
function map<T, U>(arr: readonly T[], fn: (item: T, index: number) => U): U[] {
  return arr.map(fn);
}

// Conditional types
type Unwrap<T> = T extends Promise<infer U> ? U : T;

Declaration Files

typescript
// module.d.ts
declare module "lea-lang" {
  export function run(code: string): unknown;
  export function parse(code: string): Program;
}

Common Patterns

  • •Use unknown over any for safer type narrowing
  • •Prefer interface for extendable types, type for unions
  • •Use as const for literal types
  • •Leverage satisfies for type checking without widening

Reference Files