TypeScript：掌握 `satisfies` 运算符

1// 类型定义
2type ColorMap = {
3  primary: string;
4  secondary: string;
5};
6
7// 方法1：类型注解 - 丢失精确信息
8const colors: ColorMap = {
9  primary: '#007bff',
10  secondary: '#6c757d',
11}; // 值的精确类型丢失
12
13// 方法2：无注解 - 没有验证
14const colors2 = {
15  primary: '#007bff',
16  secondary: '#6c757d',
17}; // 未对 ColorMap 进行验证

1const colors = {
2  primary: '#007bff',
3  secondary: '#6c757d',
4} satisfies ColorMap;
5
6// ✅ 验证是否符合 ColorMap
7// ✅ 保留字符串的字面量信息
8// ✅ 自动完成功能完美运行

1type Config = {
2  api: {
3    endpoint: string;
4    timeout?: number;
5  };
6  features: Record<string, boolean>;
7};
8
9const config = {
10  api: {
11    endpoint: 'https://api.example.com',
12    timeout: 5000,
13    retryCount: 3, // 允许额外属性
14  },
15  features: {
16    darkMode: true,
17    betaFeatures: false,
18  },
19} satisfies Config;
20
21// TypeScript 验证必需属性的存在
22// 同时允许额外属性

1type MediaType = 'image' | 'video' | 'audio';
2
3const MEDIA_CONFIG = {
4  image: { maxSize: 5000000, formats: ['jpg', 'png'] },
5  video: { maxSize: 50000000, formats: ['mp4', 'mov'] },
6  audio: { maxSize: 10000000, formats: ['mp3', 'wav'] },
7} satisfies Record<MediaType, { maxSize: number; formats: string[] }>;
8
9// 访问属性时保持其精确类型
10const imageFormats = MEDIA_CONFIG.image.formats; // string[]

1type Partial<T> = { [P in keyof T]?: T[P] };
2
3const partialConfig = {
4  api: { endpoint: 'https://api.example.com' },
5} satisfies Partial<Config>;

1// ❌ 限制太严格
2type StrictConfig = {
3  [K in string]: never;
4} & Config;
5
6// ✅ 更灵活
7type ExtensibleConfig = Config & Record<string, unknown>;

1type Status = 'success' | 'error';
2
3// ❌ 可能具有误导性
4const result = { status: 'success' as Status };
5
6// ✅ 更安全
7const result = { status: 'success' } satisfies { status: Status };