Question

作为我尝试的好程序员，我安装了短毛绒和哈士奇犬。当我检查短毛绒时，我到达了app.component.ts文件，并且一切都变红了。它不喜欢构造函数中的声明。好吧，没问题，我更改了：

  constructor(
    private platform: Platform,
    private splashScreen: SplashScreen,
    private statusBar: StatusBar,
  ) {
    this.initializeApp();
    }

到

  private platform: Platform;
  private splashScreen: SplashScreen;
  private statusBar: StatusBar;

  public constructor(
    platform: Platform,
    splashScreen: SplashScreen,
    statusBar: StatusBar,
    ){
     this.initializeApp();
     this.platform = platform;
     this.splashScreen = splashScreen;
     this.statusBar = statusBar;
    }

但是，更改之后，我遇到了所有类型的错误：

错误TypeError：无法读取未定义的属性“就绪”

这是指：

  public initializeApp(): void {
    this.platform.ready().then( // <----ERROR
      (): void => {
        this.statusBar.styleDefault();
        this.splashScreen.hide();
      },
    );
  }

然后我也会收到有关Type并分配给any[]

的错误

我的主要问题是为什么？为什么私有实例的构造函数声明可以，但是随后在构造函数外部私下声明它，却仍将其传递给构造函数this.platform，为什么找不到。另外，我如何能在没有抱怨的情况下获得相同的结果。

Answer 1

您必须在this.platform = platform;之前致电this.initializeApp();，否则您的私有财产将不确定。您的短毛绒应该可以使用以下代码：

public constructor(
    platform: Platform,
    splashScreen: SplashScreen,
    statusBar: StatusBar,
    ){
     this.platform = platform;
     this.splashScreen = splashScreen;
     this.statusBar = statusBar;
     this.initializeApp();
    }

Answer 2

  private platform: Platform;
  private splashScreen: SplashScreen;
  private statusBar: StatusBar;

  public constructor(
    platform: Platform,
    splashScreen: SplashScreen,
    statusBar: StatusBar,
    ){
     this.initializeApp(); // <-- initialize app called here.
     this.platform = platform; // <-- platform assigned here.
     this.splashScreen = splashScreen;
     this.statusBar = statusBar;
    }

由于在分配initializeApp之前调用了this.platform，因此它的原始值为undefined。只需在分配后后移动initializeApp：

     this.platform = platform; // <-- platform assigned here.
     this.splashScreen = splashScreen;
     this.statusBar = statusBar;
     this.initializeApp(); // <-- initialize app called here.

ionic 4错误TypeError：无法读取未定义的属性“就绪”

2 个答案: