setNumberStyle(numberStyle) {
    this._numberStyle = numberStyle;
    switch (this._numberStyle) {
      case NONE:
        this._styleDefaults = StyleDefaults.NONE;
        break;
      case PERCENT:
        this._styleDefaults = StyleDefaults.PERCENT;
        break;
      case CURRENCY:
        this._styleDefaults = StyleDefaults.CURRENCY;
        break;
      default:
        this._styleDefaults = null;
    }
    return this;
  }
Sets the number style used to configure various default setting values.

@param {string} numberStyle
@returns {NumberFormatter}