propertyName in objectName 在下面的例子中,in类型守卫检查 house 属性是否存在。如果存在,则返回布尔值true,如果不存在,则返回false。 "house" in { name: "test", house: { parts: "door" } }; // => true "house" in { name: "test", house: { parts: "windows" } }; // => true "house...
@this:描述此处this指向 @extends(或@augments):描述继承关系 @enum:描述一组关联属性 @property(或@prop):描述对象属性 P.S.完整的 JSDoc 标记列表见...Block Tags 特殊的,对于泛型,JSDoc 里没有提供合适的标记,因此扩展了额外的标记: @template:描述泛型 P.S.用@template标记描述泛型源自Google Closure......
typeReadonlyObject<T>={readonly[PinkeyofT]:T[P];};constobj:ReadonlyObject<{name:string;age:number}>={name:"Alice",age:20,};obj.name="Bob";// Error: Cannot assign to 'name' because it is a read-only property. 类型守卫 类型守卫是 TypeScript 中一种用于缩小类型范围的机制。通过使用类...
__extends) || (function () { var extendStatics = function (d, b) { extendStatics = Object.setPrototypeOf || ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) || function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] ...
在下面的例子中，name的类型并不匹配字符串索引的类型，所以类型检查器会给出报错：interface NumberDictionary { [index: string]: number; length: number; // ok name: string;// Property 'name' of type 'string' is not assignable to 'string' index type 'number'.}然而，如果一个索引签名是...
{origin:'DB-1'});// ❌save(data);/* ErrorArgument of type 'DataType' is not assignable to parameter of type 'Required<DataType>'.Types of property 'origin' are incompatible.Type 'string | undefined' is not assignable to type 'string'.Type 'undefined' is not assignable to type '...
Property'name' of type 'string' is not assignable to 'string' index type 'number'. } 但是,如果索引签名是属性类型的联合,则可以接受不同类型的属性: interface NumberOrStringDictionary { [index: string]: number|string; length: number;//ok, length is a numbername: string;//ok, name is a ...
// Property 'age' is missing in type '{ name: string; }'. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 多一些属性也是不允许的: AI检测代码解析 interface Person { name: string; age: number; } let tom: Person = { name: 'Tom', ...
};// 错误提示:Type 'Person' is not assignable to type 'PersonTypeWithAddress'.// Property 'address' is missing in type 'Person' but required in type 'PersonWithAddress'.// let p:PersonTypeWithAddress = new Person() 8、typeof使用实例类型约束 ...
这是因为一个声明类似于 obj.property 的字符串索引,跟 obj["property"]是一样的。在下面的例子中,name 的类型并不匹配字符串索引的类型,所以类型检查器会给出报错: interface NumberDictionary { [index: string]: number; length: number; // ok name: string; // Property 'name' of type 'string' is...