用ts打印族谱

以下是代码

#!/usr/bin/env ts-node
function createPrefix(n: number):string {
    return '----'.repeat(n);
}
{
    class Person {
        public children: Person[] = []; //前面是类型声明，后面必须要初始赋值，不然就是undefined
        constructor(public name: string) {}
        addChild(child: Person): void { //什么也不返回就添加void
            this.children.push(child);
        }
        introduceFamily(n?: number): void { // ?表示可选参数
            n = n || 1
            console.log(`${createPrefix(n-1)}${this.name}`)
            this.children.forEach((child)=>{
                child.introduceFamily(n+1);
            });
        }
    }

    let grandPa = new Person('王大');
    let child1 = new Person('王小');
    let child2 = new Person('王小二');
    let person1 = new Person('王小小');
    let person2 = new Person('王二二');

    grandPa.addChild(child1);
    grandPa.addChild(child2);

    child1.addChild(person1);
    child2.addChild(person2);

    grandPa.introduceFamily();
}