指定在Typescript類建構式中設定什么可選屬性

在某些情況下，我只想添加一個ImageURL，有時只想添加一個bio，有時兩者都是，有時兩者都不是。我希望這個問題和這個問題已經有點清楚了。

我希望運作的不同呼叫如下：

我希望運作的不同呼叫如下：

new Lifter("1"/span>,"Jesper"/span>, 73,107,125,220), /None of the propertiesnew Lifter("2"/span>,"Alfred"/span>,83, 187,205,220,"Some Biography"), /Biography passed.
new Lifter("3"/span>,"Manfred"/span>, 73,107,125,220, "https: //www. w3schools.com/howto/img_avatar2.png"),//ImageURL passed。
new Lifter("4"/span>,"Sigfred"/span>,73, 107,125,220,"其他一些傳記" ,"https: //www. w3schools.com/howto/img_avatar2.png"),//兩個屬性的值都通過。

為了說明問題，我只是對上面的第三種情況有意見。

uj5u.com熱心網友回復：

一種方法是通過命名引數的物件重構作業法來實作。

你的建構式對作為引數傳入的物件進行解構：

你的建構式對作為引數傳入的物件進行解構。

constructor(id: string, name: string, weightclass:number, bestSnatch:number, bestCJ:number, bestTotal:number, {bio="default bio", imageURL = "https://upload. wikimedia.org/wikipedia/commons/a/a0/Arh-avatar.jpg"/span>} = {}) {
  this.id = id;
  this.name = name;
  this.weightclass = weightclass;
  this.bestSnatch = bestSnatch;
  this.bestCJ = bestCJ;
  this.bestTotal = bestTotal;
  this.bio = bio;
  this.imageURL = imageURL;
}

而且你可以通過傳入適當的物件來這樣呼叫它：

new Lifter("1"/span>, "Jesper",73,107, 125, 220)
new Lifter("2"/span>,"Alfred"/span>, 83,187,205,220, {bio: "一些傳記"})
new Lifter("3"/span>,"Manfred"/span>, 73,107,125,220, {imageURL: "https://www.w3schools.com/howto/img_avatar2.png"})
new Lifter("4"/span>,"Sigfred"/span>, 73,107,125,220, {bio: "其他一些傳記" , imageURL: "https://www.w3schools.com/howto/img_avatar2.png"})

uj5u.com熱心網友回復：

你可以為bio傳入一個null，或者你可以像上面所說的那樣讓它成為可選項。<當你創建一個新的類的實體時，bio必須有一個值，因為這是你定義該類的方式。

new Lifter("3"/span>,"Manfred"/span>, 73,107,125,220,null, "https: //www. w3schools.com/howto/img_avatar2.png"),//ImageURL passed。

uj5u.com熱心網友回復：

除了已經描述過的方法外，還有兩種方法我只想提一下：

export class Lifter {
  id: string;
  name: string;
  weightclass: 數字。
  bestSnatch: 數字。
  bestCJ: number;
  bestTotal: 數字。
  bio: string = "默認傳記文本"。
  imageURL: string = "https://upload.wikimedia.org/wikipedia/commons/a/a0/Arh-avatar.jpg";

  private constructor(id: string, name: string, weightclass: number, bestSnatch: number, bestCJ: number, bestTotal: number) {
    this.id = id;
    this.name = name;
    this.weightclass = weightclass;
    this.bestSnatch = bestSnatch;
    this.bestCJ = bestCJ;
    this.bestTotal = bestTotal;
  }

  static create（id: string, name: string, weightclass: 數字, bestSnatch:數字, bestCJ:數字, bestTotal:數字, Bio: string, imageURL: string): Lifter {
    return new Lifter（id, name, weightclass, bestSnatch, bestCJ, bestTotal）。
  }

  static createWithDefaultBioAndImageURL（id: string，name: string, weightclass:數字, bestSnatch:數字, bestCJ:數字, bestTotal:數字）。) Lifter {
    return new Lifter（id, name, weightclass, bestSnatch, bestCJ, bestTotal）。
  }

  static createWithDefaultBio（id: string, name: string, weightclass: 數字, bestSnatch:數字, bestCJ:數字, bestTotal:數字, imageURL: string）。) Lifter {
    const lifter = new Lifter（id, name, weightclass, bestSnatch, bestCJ, bestTotal）。
    lifter.imageURL = imageURL。
    return lifter。
  }

  static createWithDefaultImageURL（id: string, name: string, weightclass: 數字, bestSnatch:數字, bestCJ:數字, bestTotal:數字, bio: string）。) Lifter {
    const lifter = new Lifter（id, name, weightclass, bestSnatch, bestCJ, bestTotal）。
    lifter.bio = bio;
    return lifter;
  }
}

const lifter1 = Lifter. create("3"/span>,"Manfred"/span>,73。 107,125,220," sampleBio", "https: //www. w3schools.com/howto/img_avatar2.png"）。)
const lifter2 = Lifter. createWithDefaultBio("3"/span>,"Manfred"/span>, 73,107,125,220, "https: //www. w3schools.com/howto/img_avatar2.png"）。)
const lifter3 = Lifter. createWithDefaultImageURL("3"/span>,"Manfred"/span>,73, 107,125,220,"sampleBio"）。)
const lifter4 = Lifter. createWithDefaultBioAndImageURL("3"/span>,"Manfred"/span>, 73,107,125,220）。)

這里的例子

export class Lifter {
  id: string;
  name: string;
  weightclass: 數字。
  bestSnatch: 數字。
  bestCJ: number;
  bestTotal: 數字。
  bio: string = "默認傳記文本"。
  imageURL: string = "https://upload.wikimedia.org/wikipedia/commons/a/a0/Arh-avatar.jpg";

  constructor(id: string, name: string, weightclass: number, bestSnatch: number, bestCJ: number, bestTotal: number, bio: string, imageURL: string) {
    this.id = id;
    this.name = name;
    this.weightclass = weightclass;
    this.bestSnatch = bestSnatch;
    this.bestCJ = bestCJ;
    this.bestTotal = bestTotal;
  }
}

export class LifterBuilder{
  id: string;
  name: string;
  weightclass: 數字。
  bestSnatch: 數字。
  bestCJ: number;
  bestTotal: 數字。
  bio: string = "默認傳記文本"。
  imageURL: string = "https://upload.wikimedia.org/wikipedia/commons/a/a0/Arh-avatar.jpg";

  constructor(id: string, name: string, weightclass: number, bestSnatch: number, bestCJ: number, bestTotal: number) {
    this.id = id;
    this.name = name;
    this.weightclass = weightclass;
    this.bestSnatch = bestSnatch;
    this.bestCJ = bestCJ;
    this.bestTotal = bestTotal;
  }

  withBio（bio: string）。LifterBuilder {
      this.bio = bio。
      return this。
  }

  withImageURL（imageURL: string）。LifterBuilder {
      this.imageURL = imageURL;
      return this。
  }

  build（）。Lifter {
      return new Lifter(this. id, this. name, this.weightclass, this。 bestSnatch, this.bestCJ, this。 bestTotal, this.bio, this.imageURL）。)
  }
}

const lifter = new LifterBuilder(. ...）.withBio（...）.withImageURL（. ...).build(); //只是在需要時呼叫withBio或withImageURL，如果你不想改變默認值就不要呼叫任何一個。

bio?: string;
imageURL?: string;

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