javascript - 在 Angular 4 中使用等待时生成器未定义错误

Question

我有一个使用 Angular 4.4.6 版本的项目。 this is version of angular

当我配置它并运行时，就可以了。但是在函数 onSubmit Login 中使用 async 和 wait 时出现问题:login.component.ts:

public async onSubmit() {
    this.submitted = true;
    if (this.form.valid) {
      const user: ILoginUser = {
        UserName: this.form.value.username,
        Password: this.form.value.password
      };
      this.isLoginSuccessful = await this._loginService.login(user, true);
    }
  }

不知道为什么抛出异常exception here 。我认为 tsconfig.json 中有问题，但我不知道我错了的确切位置。

这是 tsconfig.json:

{
  "compileOnSave": false,
  "compilerOptions": {
    "outDir": "./dist/out-tsc",
    "baseUrl": "src",
    "sourceMap": true,
    "declaration": false,
    "moduleResolution": "node",
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "noEmit": true,
    "noEmitHelpers": false,
    "target": "es5",
    "typeRoots": [
      "node_modules/@types"
    ],
    "lib": [
      "es2016",
      "dom"
    ],
    "plugins": [
      {
        "name": "tslint-language-service"
      }
    ]
  },
  "exclude": [
    "node_modules",
    "dist"
  ],
  "awesomeTypescriptLoaderOptions": {
    "forkChecker": true,
    "useWebpackText": true
  },
  "buildOnSave": false,
  "atom": {
    "rewriteTsconfig": false
  }
}

Everyone please help me, many thanks!

Answer 1

我建议使用订阅而不是使用异步和等待。如果您遇到任何错误，请告诉我。

await works for promise, while your login function must be returning an observable, so you might want to convert the observable to promise, if you must use await like:
>> await .login(,,).toPromise()

public onSubmit() {
  this.submitted = true;
  if (this.form.valid) {
    const user: ILoginUser = {
      UserName: this.form.value.username,
      Password: this.form.value.password
    };
    this._loginService.login(user, true).subscribe((bool) => {
      this.isLoginSuccessful = bool;
    });
  }
}