【TypeScript】TypeScript进阶

在TypeScript中，进阶主要涉及更复杂的类型系统、工具和最佳实践。以下是一些进阶主题的示例代码：

1. 类型保护 (Type Guards)

function isFish(pet: Fish | Bird): pet is Fish {
    return (pet as Fish).swim !== undefined;
}
 
let pet = getSmallPet();
 
if (isFish(pet)) {
    pet.swim();
} else {
    pet.fly();
}

2. 类型断言

let fishPet = <Fish>getSmallPet();
fishPet.swim();

3. 泛型

function createMap<Key, Value>(initialData: Map<Key, Value>): Map<Key, Value> {
    let newMap = new Map<Key, Value>();
    initialData.forEach((value, key) => newMap.set(key, value));
    return newMap;
}
 
let stringMap = createMap<string, number>([
    ["one", 1],
    ["two", 2]
]);

4. 接口 vs. 类

interface Point {
    x: number;
    y: number;
}
 
class PointClass implements Point {
    x: number;
    y: number;
 
    constructor(x: number, y: number) {
        this.x = x;
        this.y = y;
    }
}

5. 混合类型

type Descriptor = 
    { kind: "number", value: number } |
    { kind: "string", value: string };
 
let numberDescriptor: Descriptor = { kind: "number", value: 123 };
let stringDescriptor: Descriptor = { kind: "string", value: "hello" };

6. 类型别名

type Point = {
    x: number;
    y: number;
};
 
let origin: Point = { x: 0, y: 0 };

这些代码示例展示了TypeScript中的一些高级特性，它们可以用来构建复杂的类型和应用程序。