whole_func_string: function (el) {
    this.el = el
    if(typeof el.classList !== 'undefined') {
      // if classList support
      this.old = false
    } else {
      // browser class unsupport classList
      this.classList = new nativeClasList(el)
      this.old = true
    }
  }
func_code_string: function (el) {
    this.el = el
    if(typeof el.classList !== 'undefined') {
      // if classList support
      this.old = false
    } else {
      // browser class unsupport classList
      this.classList = new nativeClasList(el)
      this.old = true
    }
  }
func_documentation_string: define classList object