onBeforeRendering() {
      if (this.startValue > this.endValue) {
        const affectedValue = this._valueAffected === "startValue" ? "endValue" : "startValue";
        this._swapValues();
        this._setAffectedValue(affectedValue);
        this.update(affectedValue, this.startValue, this.endValue);
      }
      if (!this.isCurrentStateOutdated()) {
        return;
      }
      this.notResized = true;
      this.syncUIAndState();
      this._updateHandlesAndRange(0);
    }
Check if the previously saved state is outdated. That would mean
either it is the initial rendering or that a property has been changed
programmatically - because the previous state is always updated in
the interaction handlers.

Normalize current properties, update the previously stored state.
Update the visual UI representation of the Slider.