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Typescript:使用类中的默认值初始化对象

typescript javascript

0

Vincent Tang · 技术社区 · 6 年前

如何创建一个typescript类/js来初始化具有默认属性的对象? 当前正在使用带有typescript参数的类

e、这是我的课

export class StateModel {
  stateID: number;
  stateCode: string;
  stateName: string;
  stateTwoCharCode: string;

  constructor(
    stateId: number, 
    stateCode: string = '', 
    stateName: string = '',
    stateTwoCharCode: string = ''){
    this.stateID = stateId;
    this.stateCode = stateCode;
    this.stateName = stateName;
    this.stateTwoCharCode = stateTwoCharCode;
  }
}

在我导入它的代码中,我想调用如下内容:

let newClass = new StateModel();

如果我用控制台记录 newClass 我期待以下结果:

newClass = {
  stateCode: '',
  stateName: '',
  stateTwoCharCode: ''
}

但理想情况下,我希望参数对构造函数是可选的

0 回复 | 直到 6 年前

1

0

Oscar Velandia 6 年前

您可以使用可选选项 parameters ,在您的代码中,唯一缺少的是专用键盘:

export class StateModel {
  stateID: number;
  stateCode: string;
  stateName: string;
  stateTwoCharCode: string;

  constructor(
    stateId: number, 
    private stateCode: string = '', 
    private stateName: string = '',
    private stateTwoCharCode: string = ''){
    this.stateID = stateId;
    this.stateCode = stateCode;
    this.stateName = stateName;
    this.stateTwoCharCode = stateTwoCharCode;
  }
}

2

0

azer-p 6 年前

您的可选参数代码正在运行。你只需要这样开始

newClass: StateModel = new StateModel(1);

3

0

Vincent Tang 6 年前

https://www.typescriptlang.org/play/?ssl=1&ssc=1&pln=11&pc=32#code/KYDwDg9gTgLgBAYwDYEMDOa4GUYpsAWQgBNgk4BvAKDkQgDs0YoBXBGaAChtrjBYBGSAJYI4TPMACSxAFxx6LALYDgUADRwetfkNHjc+AMIlg8plGH0A5nAC8cAOSPN2vpYBukg5IByKJTMDSxt7Jxc3ME9vCXwAFQB3CCMACxQoE1JzZitbB2cASmoeAF8qMqoEBiY4ADMICDD6YATsQ0JTJE4ARgAmAGYCoA

如果我用打字机写的话

export class StateModel {
  constructor(
    public stateId: number, 
    public stateCode: string = '', 
    private stateName: string = '',
    private stateTwoCharCode: string = ''){

  }
}

const foo = new StateModel(123)
console.log(foo,"foo")

它用javascript编译成这样

export class StateModel {
    constructor(stateId, stateCode = '', stateName = '', stateTwoCharCode = '') {
        this.stateId = stateId;
        this.stateCode = stateCode;
        this.stateName = stateName;
        this.stateTwoCharCode = stateTwoCharCode;
    }
}
const foo = new StateModel(123);

登录中 foo 显示预期的对象结构