In typescript, keyof is defined as indexed type query operator for any object type this keyof the object type would be the union of properties of object names and this also works with object type for user properties which produces the type literal union of its keys and the type here may b...
functionprintUser(user:User){Object.keys(user).forEach((key)=>{// 不起作用!console.log(user[key]);// 出错信息如下:// Expression implicitly has an 'any' type because expression of type 'string' can't be used to index type 'User'.// No index signature with a parameter of type 'str...
// type keys = "x" | "y" type keys = keyof Point; 1. 2. 3. 4. 5. 6. 假设我们有一个如下所示的对象,我们需要使用 typescript 实现一个 get 函数来获取其属性的值。 const data = { a: 3, hello: 'max' } function get(o: object, name: string) { return o[name] } 1. 2. 3...
同样，Assertarg as keyof T不是真的。如果你不Assert，那么编译器会抱怨，因为arg不知道是Object.keys...
*/export{};constlog =console.log;// The keyof operator takes an `object type` and produces a `string` or `numeric literal union` of its keys.typePoint= {x:number;y:number};constpoint:Point= {x:1,y:2, }typeP = keyofPoint;// type P === type as “x” | “y” ❓// cons...
To work around this restriction, the simplest solution is to use type assertion with the keyof operator: type userKeyType = keyof typeof user; // "name" | "age" Object.keys(user).forEach((key) => { console.log(user[key as userKeyType]) }) A more elegant solution is to extend th...
type keys = keyof Point; 假设我们有一个如下所示的对象,我们需要使用 typescript 实现一个 get 函数来获取其属性的值。 const data = { a: 3, hello: 'max' } function get(o: object, name: string) { return o[name] } 我们一开始可能是这样写的,但它有很多缺点: ...
interfacePoint {x:number;y:number;}// type keys = "x" | "y"typekeys = keyof Point; 假设我们有一个如下所示的对象,我们需要使用 typescript 实现一个 get 函数来获取其属性的值。 constdata= {a:3,hello:'max'}functionget(o:object, name: string) {...
type Keys = "a" | "b" | "c"; // 使用in遍历Keys联合类型,为每个键生成一个string类型的属性 type DynamicObject = { [P in Keys]: string; }; // DynamicObject的类型等价于: // { // a: string; // b: string; // c: string; ...
01 keyof keyof 与 Object.keys 略有相似,只不过 keyof 取 interface 的键。...: T[P];}; type Required = { [P in keyof T]-?...Use Workspace Version,它表示与项目依赖的 typescript 版本一直。...或者编辑 .vs-code/settings.json { "typescript.tsdk": "node_modules/typescript/lib"} 11 ...