Javascript 何时执行typescript/js装饰程序

装饰师什么时候被处决

class Person {
    @SomeDecorator
    age
}

当我创建Person的实例时

当分析Person类时

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静态属性呢？

属性装饰器在定义类时提前执行。您不需要构造实例或访问属性

示例：此日志记录了

age

，甚至没有构建

Person

类。如果属性是静态的，则同样适用

function SomeDecorator(a, b) {
    console.log(b);
}

class Person {
    @SomeDecorator
    public age: number;
}

如果您是在钩住属性上的get和set操作之后-这也是可能的。下面是中的一个列表示例。它通过包装getter和setter来工作

function log(target: any, key: string) {
    let value = target[key];

    // Replacement getter
    const getter = function () {
        console.log(`Getter for ${key} returned ${value}`);
        return value;
    };

    // Replacement setter
    const setter = function (newVal) {
        console.log(`Set ${key} to ${newVal}`);
        value = newVal;
    };

    // Replace the property
    if (delete this[key]) {
        Object.defineProperty(target, key, {
            get: getter,
            set: setter,
            enumerable: true,
            configurable: true
        });
    }
}

class Calculator {
    @log
    public num: number;

    square() {
        return this.num * this.num;
    }
}

console.log('Construct');
const calc = new Calculator();

console.log('Set');
// Set num to 4
calc.num = 4;

console.log('Get');
// Getter for num returned 4
// Getter for num returned 4
calc.square();

此列表的输出为：

Construct (manual log)

Set (manual log)

-> Set num to 4

Get (manual log)

-> Getter for num returned 4

-> Getter for num returned 4

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什么是静态类？@Bergi Sry，我指的是静态属性上的装饰器