Method renderAsync

resources/vega.min.js:14306–14309

(t, e)

    }
    _render() {}
    renderAsync(t, e) {
      const n = this.render(t, e);
      return this._ready ? this._ready.then(() => n) : Promise.resolve(n);
    }
    _load(t, e) {
      var n = this,
        r = n._loader[t](e);