TypeScript类构造函数中的可选参数

Question

有没有一种方法可以减轻TypeScript中可选参数的顺序？我现在有这门课

export default class Area {
    private name: string;
    private description: string;
    private item?: Item;
    private hazard?: Hazard;

    constructor(name: string, description: string, item?: Item, hazard?: Hazard) {
        this.name = name;
        this.description = description;
        this.item = item;
        this.hazard = hazard;
    }
}

对于这个区域类，我需要name和string参数，但不需要item或hazard参数。我尝试通过以下方式实例化一个Area对象：

let item = new Item(); // had required parameters, but not important for now
let hazard = new Hazard(); // had required parameters, but not important for now

let area = new Area("test", "test"); // works as expected
let area1 = new Area("test", "test", item); // works as expected
let area2 = new Area("test", "test", hazard); // DOES NOT WORK as expected
let area3 = new Area("test", "test", item, hazard); // works as expected

尽管hazard和item是可选的，但如果我想省略item，则需要为第三个参数传入undefined。是否有减轻或放弃这种行为，我们可以传递与任何可选参数匹配的第三个参数？

Answer 1

由类型记录完成的类型检查只存在于类型记录中，在编译的Javascript中不存在，因此如果允许的话，Javascript将无法确定您实际上试图传递哪个参数。

相反，传递一个具有item或hazard属性的可选对象：

class Item{}
class Hazard{}

export default class Area {
    private name: string;
    private description: string;
    private item?: Item;
    private hazard?: Hazard;

    constructor(
      name: string,
      description: string,
      obj: { item?: Item, hazard?: Hazard } = {}
    ) {
        this.name = name;
        this.description = description;
        if (obj.item) this.item = obj.item;
        if (obj.hazard) this.hazard = obj.hazard;
    }
}

const item = new Item();
const hazard = new Hazard();

const area = new Area("test", "test"); 
const area1 = new Area("test", "test", { item });
const area2 = new Area("test", "test", { hazard });
const area3 = new Area("test", "test", { item, hazard });