在这种情况下,Record<Keys, Type> 可以用来定义角色和权限的类型,从而确保整个应用程序的类型安全。 代码语言:javascript 代码运行次数:0 运行 AI代码解释 // 定义一组角色type UserRole='admin'|'editor'|'viewer';// 定义权限为结构化对象type Permission={canCreate:boolean;canRead:boolean;canUpdate:boolean;ca...
问typescript索引签名与Record<Keys，Type>返回具有未知属性的对象的类型EN本章节要介绍的内容为 TS 接口...
function getValues(obj: any, keys: string[]) { return keys.map(key => obj[key]) } // obj 中存在的属性 console.log(getValues(obj, ['a', 'b'])); // [ 1, 2 ] // obj 中不存的属性,返回 undefined,而没有提示报错 console.log(getValues(obj, ['e', 'f'])); // [ undefine...
type Keys = "a" | "b" | "c" type Obj = { [p in Keys]: any } // -> { a: any, b: any, c: any } 4.infer 在条件类型语句中,可以用infer声明一个类型变量并且对它进行使用。 type ReturnType<T> = T extends ( ...args: any[] ) => infer R ? R : any; 以上代码中infer ...
} let pet = getSmallPet(); pet.layEggs(); // okay pet.swim(); // errors 这里的联合类型可能有点复杂,但是你很容易就习惯了。如果一个值的类型是A | B,我们能够确定的是它包含了A和B中共有的成员。这个例子里,Bird具有一个fly成员。我们不能确定一个Bird | Fish类型的变量是否有fly方法。如果变...
interfaceContext{name:string;metadata:Record<PropertyKey,unknown>; }functionsetMetadata(_target:any,context:Context) { context.metadata[context.name] =true; }classSomeClass{@setMetadatafoo =123;@setMetadataaccessor bar ="hello!";@setMetadatabaz(...
// Ensure that we have exactly the keysfrom'Colors'. const favoriteColors = { "red": "yes", "green":false, "blue": "kinda", "platypus":false// ~~~ error - "platypus" was never listedin'Colors'. } satisfiesRecord<Colors,unknown>; //Allthe ...
Bug Report When creating a object with symbols for keys and explicitly telling typescript the object should be of type Record<string, string>. Typescript fails to throw an error. Is does however throw an error when you use the symbol to ...
TypeScript Version: 2.1.5 What I'd like to do is effectively extend from a record type and then add a few more custom properties. Since type aliases cannot by extended, I tried solving the problem with an indexed type signature in the in...
```function applyStringMapping(symbol: Symbol, str: string) {switch (intrinsicTypeKinds.get(symbol.escapedName as string)) {case IntrinsicTypeKind.Uppercase:return str.toUpperCase();case IntrinsicTypeKind.Lowercase:return str.toLowerCase();case IntrinsicTypeKind.Capitalize:return str.charAt(0)....