getElementsByTagName vs. getElementsByName

上一篇"多個RadioButtonList設為相同Group"裡面有用到getElementsByTagName
有人會說既然有把name(即paramOldName)傳入，何不直接使用getElementsByName
就不需要多這個判斷式

 
  if(ObjArray[i].type == "radio" && ObjArray[i].name == paramOldName)

這裡說一下理由 (這部份要感謝昌琰)
因為getElementsByName找到的Object只能改name以外的屬性!!
我試過了連ID也可以改，就是只有name不能被修改
所以只好用getElementsByTagName收集大範圍的物件，再透過if判斷式過濾
By Felix

把多個RadioButtonList設為相同Group

問題: 如果頁面上有多組RadioButtonList，要做到這幾組RadioButtonList間都只能單選，例如:
50cc機車 125cc機車 150cc以上機車

休旅車 跑車 房車

如果上下兩排各是一個RadioButtonList如何讓他們都屬與同一group
當然，我們可以只用html的radio button做到，只要name屬性設為一樣。但是如果想透過程式動態產生那些選項，RadioButtonList還蠻好用的。可惜它沒有name or groupname這個property可用!

我的作法是做一個含RadioButtonList的UserControl:

 Partial Class UCRadioBtnList
       Inherits System.Web.UI.UserControl

   Private _GroupName As String

   '提供設定RadioButton項目
    Public WriteOnly Property Items() As String()
      Set(ByVal value As String())
        Dim ItemTemp As ListItem
        
        For Each v As String In value
           ItemTemp = New ListItem(v)
           Me.RadioButtonList.Items.Add(ItemTemp)
        Next
     End Set End Property

   '提供設定RadioButtonList的RroupName
   Public Property GroupName() As String
     Get
       Return Me._GroupName
     End Get
     Set(ByVal value As String)
        Me._GroupName = value
        '把GropuName存在ViewState中，預防postback時消失
         If IsNothing(Me.ViewState("GroupName")) Then
          Me.ViewState("GroupName") = value
        End If
     End Set
   End Property

 '註冊一行會呼叫 function SetSameGroup( )的script到畫面
 Private Sub SetSameGroup()
   Dim StrScript As String

   StrScript = "SetSameGroup('" & Me.ClientID & "$RadioButtonList','" &
   Me.ViewState ("GroupName") & "');" & vbNewLine
   ScriptManager.RegisterStartupScript(Me.Page, Me.Page.GetType(),     Me.RadioButtonList.ClientID, StrScript, True)
 End Sub

 '畫面載入時都在註冊一次script(因為script在postback後就會自動消失)
 Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
   Me.SetSameGroup()
 End Sub

 End Class

//javascript

function SetSameGroup(paramOldName, paramGroupName) {
  var ObjArray = document.getElementsByTagName("Input");
  var StrTemp;
  for (i = 0; i < ObjArray.length; i++) {
    if(ObjArray[i].type == "radio" && ObjArray[i].name == paramOldName) {
      StrTemp = ObjArray[i].parentNode.innerHTML.replace(paramOldName,   paramGroupName); 
      ObjArray[i].parentNode.innerHTML = StrTemp;
    } 
  } 
}

使用這個UserControl的畫面的.vb檔

  Dim ArrayListSource1 As String() = {"aa", "bb", "cc", "dd"} 
  Dim ArrayListSource2 As String() = {"ee", "ff", "gg", "hh"}

  Me.UCRadioBtnList1.Items = ArrayListSource1 '加入選項
  Me.UCRadioBtnList2.Items = ArrayListSource2
  Me.UCRadioBtnList1.GroupName = "sss"        '設定GroupName
  Me.UCRadioBtnList2.GroupName = "sss"

By Felix