打字稿 - 更好的是：获取/设置属性

Question

最近刚刚发现关于对类属性使用 get 和 set 关键字我想知道在 typescript 类中使用 get/set 时的首选方法是什么：

class example {
    private a: any;
    private b: any;

    getA(): any{
        return this.a;
    }

    setA(value: any){
        this.a = value;
    }

    get b(): any{
        return this.b;
    }

    set b(value: any){
        this.b = value;
    }
}

我只是好奇是否有任何最佳实践、性能或其他因素。

Answer 1

Getter 和 Setter 有多种用途，例如

如果不指定 setter，则可以将私有变量设为只读

class example {
    private _a: any;

    get a(): any{
        return this._a;
    }
}

当变量发生变化时，您可以使用它们来执行自定义逻辑，类似于 Event Emitter 的替代品

class example {
    private _a: any;

    set a(value: any){
        this._a = value;

        // Let the world know, I have changed
        this.someMethod();
    }

    someMethod() {
        // Possibly a POST API call
    }
}

您可以使用它们为输出设置别名

class Hero {
    private _health: any = 90;

    get health(): string {
        if(this._health >= 50) {
            return "I am doing great!";
        } else {
            return "I don't think, I'll last any longer";
        }
    }
}

setter 可用于干净的赋值

class Hero {
    private _a: number;

    set a(val: number) {
        this._a = val;
    }

    setA(val: number) {
        this._a = val;
    }

    constructor() {
        this.a = 30;    // Looks cleaner
        this.setA(50);  // Looks Shabby, Method's purpose is to perform a logic not handle just assignments
    }
}

最后，setter 最大的优势是能够在赋值之前检查变量的正确值

class Hero {
    private _age: number;

    set age(age: number) {
        if (age > 0 && age < 100) {
            this._age = age
        } else {
            throw SomeError; 
        }
    }
}