Function signal

resources/vega.min.js:29678–29681

(t, e, n)

      return this._origin.slice();
    },
    signal(t, e, n) {
      const r = Rz(this, t);
      return 1 === arguments.length ? r.value : this.update(r, e, n);
    },
    width(t) {
      return arguments.length ? this.signal("width", t) : this.signal("width");
    },