Typescript:扩展抽象类时使用'this‘

abstract class Animal {
    abstract makeSound(): void;

    move(distanceInMeters: number = 0) {
        console.log(`Animal moved ${distanceInMeters}m.`);
    }
}

class Dog extends Animal {
    makeSound() {
        console.log('Woof! Woof!');
    }

    bark() {
        console.log('Barking...');
        this.makeSound(); // 使用 'this' 调用继承的方法
    }
}

const dog = new Dog();
dog.bark(); // 输出: Barking... Woof! Woof!
dog.move(10); // 输出: Animal moved 10m.

class MyClass {
    value = 42;

    printValue() {
        setTimeout(function() {
            console.log(this.value); // 这里的 'this' 不是 MyClass 的实例
        }, 100);
    }
}

const instance = new MyClass();
instance.printValue(); // 输出: undefined

class MyClass {
    value = 42;

    printValue() {
        setTimeout(() => {
            console.log(this.value); // 正确输出: 42
        }, 100);
    }
}

class MyClass {
    value = 42;

    printValue() {
        setTimeout(function() {
            console.log(this.value);
        }.bind(this), 100);
    }
}