TS2334类型“对象”上不存在属性“长度”。 仅在应用启动时（ng-serve）

Question

I'm having an issue when I start my angular app.

I have a function that does a post request, returns some data to my component and plots a chart. It works fine after I start the app do some random modification and save, but when I first start the app I get Property 'length' does not exist on type 'Object'. on a for loop I have on my response array.

I've tried iterating through the response, only if it's not null, but that didn't work.

function:

dailyForecast() {
  var token = {token : "0a1b2c3d"};
  return this._http.post("https://www.improving.com.br/api/test/hits-by-browser", token)
  .map(result => result);
}

I get the error inside this for loop, but it works fine after I re-compile.

ngOnInit() {
  let chart = < any > {};
  this._weather.dailyForecast()
    .subscribe(res => {
      console.log(res);
      let browsers = [];
      let browsersAcesss = [];
      if (res !== null) {
        for (var i = 0; i < res.length; i++) {
          browsers.push(res[i][0]);
          browsersAcesss.push(res[i][1]);
        }
      }
    });
}

Answer 1

If you want to avoid the compile error you can set the response type to any[] or a custom interface.

ngOnInit() {
  let chart = < any > {};
  this._weather.dailyForecast()
    .subscribe((res: any[]) => {
      console.log(res);
      let browsers = [];
      let browsersAcesss = [];
      if (res !== null) {
        for (var i = 0; i < res.length; i++) {
          browsers.push(res[i][0]);
          browsersAcesss.push(res[i][1]);
        }
      }
    });
}