Use fetch In A JavaScript Class

export class Widget {
  constructor() {
    this._data = null;
    this.init().then(({data}) => {
      this._data = data;
      this.ping();
    })
  }

  ping() {
    console.log(this._data);
  }

  async init() {
    const response = await fetch('/data/stations.json');
    if (!response.ok) {
      throw new Error('There was a problem getting the data')
    };
    const data = await response.json();
    return { data }
  }
}