typescript - 分配 Typescript 构造函数参数

Question

我有接口(interface):

export interface IFieldValue {
    name: string;
    value: string;
}

我有一个实现它的类:

class Person implements IFieldValue{
    name: string;
    value: string;
    constructor (name: string, value: string) {
        this.name = name;
        this.value = value;
    }
}

看完this post我在考虑重构:

class Person implements IFieldValue{
    constructor(public name: string, public value: string) {
    }
}

问题:在头等舱中，我有默认情况下应为 private 的字段。在第二个示例中，我只能将它们设置为 public。我对 TypeScript 中默认访问修饰符的理解是否完全正确？

Answer 1

Public by default.TypeScript Documentation

定义如下

class Person implements IFieldValue{
    name: string;
    value: string;
    constructor (name: string, value: string) {
        this.name = name;
        this.value = value;
    }
}

属性 <Person>.name和 <Person>.value默认情况下是公开的。

因为他们在这里

class Person implements IFieldValue{
    constructor(public name: string, public value: string) {
        this.name = name;
        this.value = value;
    }
}

注意:这是一种不正确的做法，因为 this.name和 this.value将被视为未在构造函数中定义。

class Person implements IFieldValue{
    constructor(name: string, value: string) {
        this.name = name;
        this.value = value;
    }
}

要使这些属性成为私有(private)属性，您需要将其重写为

class Person implements IFieldValue{
    private name: string;
    private value: string;
    constructor (name: string, value: string) {
        this.name = name;
        this.value = value;
    }
}

或等效

class Person implements IFieldValue{
    constructor (private name: string, private value: string) {}
}

对于 TypeScript 2.X，由于接口(interface)具有公共(public)属性，您需要更改 private至 public还有export类

export class Person implements IFieldValue{
    constructor (public name: string, public value: string) {}
}

在我看来，这是避免冗余的最佳方式。