Question

我有一个在节点上运行的打字稿应用程序。

我正在使用'EventEmitter'类来发出变量值的更改。

这是我的代码，

import events from 'events';

public async updateStream(streamContext: string, state: boolean): Promise<string> {
    const eventEmitter = new events.EventEmitter();
    if (state === true) {
      return StreamManagement.instance.activeStreams.get(streamContext).streamState = 'Paused';
    } else {
      const streamState = StreamManagement.instance.activeStreams.get(streamContext).streamState = 'Active';
      eventEmitter.emit('resume');
      return streamState;
    }
  }

 public async waitForStreamActive(stream: Stream) {
    const eventEmitter = new events.EventEmitter();
    // tslint:disable-next-line:no-unused-expression
    return new Promise(( resolve ) => {
      eventEmitter.on('resume', resolve );
    });
  }

这段代码构建良好。但是，当我像执行操作一样运行代码时，出现以下错误，

error: errorHandler - Apply - Hit Unhandled exception {"timestamp":"2019-04-29T12:33:49.209Z"}
error: errorHandler - Apply - Cannot read property 'EventEmitter' of undefined - TypeError: Cannot read property 'EventEmitter' of undefined
    at StreamResource.updateStream (C:\Vertigo\core\reference_platform\dist\index.js:10695:51)
    at StreamService.patchStream (C:\Vertigo\core\reference_platform\dist\index.js:22524:40)
    at process._tickCallback (internal/process/next_tick.js:68:7) {"timestamp":"2019-04-29T12:33:49.215Z"}

我在做什么错了？

Answer 1

我已经设置了最小的项目来重现它，并且ts编译器立即警告我：

TS1192: Module '"events"' has no default export.

但这似乎可行：

import * as EventEmitter from 'events'

new EventEmitter();

TypeError：无法读取未定义打字稿nodejs的属性“ EventEmitter”

1 个答案: