initConstants () {
    super.initConstants()

    this.constants.classes.buttonsGroup = 'buttons has-addons'
    this.constants.classes.buttonsDropdown = 'button dropdown is-right'
    this.constants.classes.input = 'input'
    this.constants.classes.paginationDropdown = 'ui dropdown'
    this.constants.classes.dropup = 'is-up'
    this.constants.classes.dropdownActive = 'is-active'
    this.constants.classes.paginationActive = 'is-current'
    this.constants.classes.buttonActive = 'is-active'

    this.constants.html.toolbarDropdown = ['<div class="dropdown-menu"><div class="dropdown-content">', '</div></div>']
    this.constants.html.toolbarDropdownItem = '<label class="dropdown-item dropdown-item-marker">%s</label>'
    this.constants.html.toolbarDropdownSeparator = '<li class="dropdown-divider"></li>'
    this.constants.html.pageDropdown = ['<div class="dropdown-menu"><div class="dropdown-content">', '</div></div>']
    this.constants.html.pageDropdownItem = '<a class="dropdown-item %s" href="#">%s</a>'
    this.constants.html.dropdownCaret = '<span class="icon is-small"><i class="fas fa-angle-down" aria-hidden="true"></i></span>'
    this.constants.html.pagination = ['<ul class="pagination%s">', '</ul>']
    this.constants.html.paginationItem = '<li><a class="page-item pagination-link%s" aria-label="%s" href="#">%s</a></li>'
    this.constants.html.searchInput = '<p class="control"><input class="%s input-%s" type="search" placeholder="%s"></p>'
    this.constants.html.inputGroup = '<div class="field has-addons has-addons-right">%s%s</div>'
    this.constants.html.searchButton = '<p class="control"><button class="%s" type="button" name="search" title="%s">%s %s</button></p>'
    this.constants.html.searchClearButton = '<p class="control"><button class="%s" type="button" name="clearSearch" title="%s">%s %s</button></p>'
  }
@author zhixin wen <wenzhixin2010@gmail.com>
https://github.com/wenzhixin/bootstrap-table/
theme: https://github.com/jgthms/bulma/