getRowValue(className) {
    if (className) {
      const rowClass = this.getRowClass(className)
      if (rowClass) {
        return rowClass.split('-')[1]
      }
    }
    return '0'
  }
Return the row value i.e row-2 would return '2'
@param {string} className
@returns {string} Row value as string or '0' for invalid definitions