javascript - 在 Angular 2 中，response.json() 是做什么的？

Question

这是来自 app/toh/hero.service.ts 的 angular 2 http 指南:

...
@Injectable()
export class HeroService {
  private heroesUrl = 'app/heroes';  // URL to web API
  constructor (private http: Http) {}
  getHeroes (): Observable<Hero[]> {
    return this.http.get(this.heroesUrl)
                    .map(this.extractData)
                    .catch(this.handleError);
  }
  private extractData(res: Response) {
    let body = res.json();
    return body.data || { };
  }
  private handleError (error: Response | any) {
   ...
  }

}

请引用 let body = res.json();从 API 中，我无法在 Response 对象上找到任何 json() 方法。从响应源我确实找到了这个:

export var Body = (function () {
    function Body() {
    }
    /**
     * Attempts to return body as parsed `JSON` object, or raises an exception.
     */
    Body.prototype.json = function () {
        if (isString(this._body)) {
            return Json.parse(this._body);
        }
        if (this._body instanceof ArrayBuffer) {
            return Json.parse(this.text());
        }
        return this._body;
    };

这两个有什么关系？

Answer 1

我查看了 node_modules/@angular/http/src 并一直在寻找

export var Response

在文件 static_response.js 中发现。它说:

export var Response = (function (_super) {
__extends(Response, _super);
function Response(responseOptions) {
    _super.call(this);
    this._body = responseOptions.body;
    this.status = responseOptions.status;
    this.ok = (this.status >= 200 && this.status <= 299);
    this.statusText = responseOptions.statusText;
    this.headers = responseOptions.headers;
    this.type = responseOptions.type;
    this.url = responseOptions.url;
}
Response.prototype.toString = function () {
    return "Response with status: " + this.status + " " + this.statusText + " for URL: " + this.url;
};
return Response;
}(Body));

在同一个文件中__extends定义如下:

var __extends = (this && this.__extends) || function (d, b) {
    for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p];
    function __() { this.constructor = d; }
    d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
};

所以 Body 有 json() & Response 通过复制的方式从 Body 中获取。