Here is a complete example of a Typescript dictionary.// Define the dictionary interface interface IDictionary { [index: string]: number; } // Create a dictionary to store the ages of people let ageDictionary: IDictionary = {}; // Populate the dictionary ageDictionary["Alice"] = 25; ageD...
Tuples become very useful when we want to create a dictionary or a key-value pair. Using our example from above, we can have an array of user names and their ids without mistakenly passing in a different type to create problems later. 当我们要创建字典或键值对时,元组变得非常有用。 使用上...
let mySquare= createSquare({ colour: "red", width: 100 });//Argument of type '{ colour: string; width: number; }' is not assignable to parameter of type 'SquareConfig'.//Object literal may only specify known properties, but 'colour' does not exist in type 'SquareConfig'. Did you ...
The Record type in TypeScript is used to create a dictionary of key-value pairs, where the keys and values can have specific types. A Record type is essentially an object type, but it provides a way to specify the types of the keys and values for better type checking and code readabilit...
function create<Type>(c: { new (): Type }): Type { return new c(); } 下面是一个更复杂的例子,使用原型属性推断和约束,构造函数和类实例的关系。 classBeeKeeper{hasMask:boolean=true;}classZooKeeper{nametag:string="Mikle";}classAnimal{numLegs:number=4;}classBeeextendsAnimal{keeper:BeeKeeper=ne...
getProperty(x, "a"); // okay getProperty(x, "m"); // error: Argument of type 'm' isn't assignable to 'a' | 'b' | 'c' | 'd'. 在泛型里使用类类型 在TypeScript使用泛型创建工厂函数时,需要引用构造函数的类类型。比如, function create(c: {new(): T; }): T { ...
: number; } function createSquare(config: SquareConfig): {color: string; area: number} { var newSquare = {color: "white", area: 100}; if (config.color) { newSquare.color = config.color; } if (config.width) { newSquare.area = config.width * config.width; } return newSquare; }...
一个相似的例子,我们可能想把泛型参数当作整个接口的一个参数。 这样我们就能清楚的知道使用的具体是哪个泛型类型(比如:Dictionary而不只是Dictionary)。 这样接口里的其它成员也能知道这个参数的类型了。 interfaceGenericIdentityFn<T> { (arg: T): T;
// error: 'colour' not expected in type 'SquareConfig'letmySquare = createSquare({ colour:"red", width:100}); 绕开这些检查非常简单。 最简便的方法是使用类型断言: letmySquare = createSquare({ width:100, opacity:0.5} as SquareConfig); ...
functioncreate<T>(c:{new():T;}):T{returnnewc();} 一个更高级的例子,使用原型属性推断并约束构造函数与类实例的关系。 classBeeKeeper{hasMask:boolean;}classZooKeeper{nametag:string;}classAnimal{numLegs:number;}classBeeextendsAnimal{keeper:BeeKeeper;}classLionextendsAnimal{keeper:ZooKeeper;}functioncreat...