无法读取未定义的属性停止-从类内部调用静态方法时 [英] Cannot read property stop of undefined - when calling a static method from inside class

问题描述

由于某种原因，当我运行此代码时，即使不首先调用startRecording方法，也会在页面加载后立即出现此错误。

For some reason, when I run this code, even without first calling the startRecording method it gives me this error right after the page has loaded.

未捕获的TypeError：无法读取未定义的比例停止。

Uncaught TypeError: Cannot read proporty 'stop' of undefind.

我认为这与范围有关，但我不确定。 startRecording方法工作正常，但在stopRecording中发现问题。

I think it has something to do with scope but I'm not sure. The startRecording method works fine but it finds a problem in stopRecording.

RecorderClass

class RecorderClass
{
    constructor() {
        this.rec = ''
    }

    static startRecording() {
        this.rec = new Recorder()
        this.rec.record()
    }

    static stopRecording() {
        this.rec.stop() // stop() of undefined
    }
}

app.js

import RecorderClass from './RecorderClass.js'
recButton.addEventListener("click", RecorderClass.startRecording())

推荐答案

您应在类范围内声明Recorder引用，以便停止记录方法可以使用它。

You should declare Recorder reference in the scope of class, so that stop recording method can use it.

 public class RecorderClass
{
    static Recorder rec;
    public RecorderClass()
    {
    }

    public static void startRecording()
    {
        rec = new Recorder();
        rec.record();
    }

    public static void stopRecording()
    {
        rec.stop();// stop() of undefined
    }
}

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