求javascript代码。（一checkbox点中后，其它几个checkbox也自动选中，）

[fujianhua168]

求javascript代码。（一checkbox点中后，其它几个checkbox也自动选中，）
　　　现有一checkbox(html格式）ID＝“a",name="a"
　　另有一组checkbox(n个）
　　　ID分别为B1,B2,B3,B4,B5,..........Bn
求一javascript代码。
　　 当a选中后，另一组checkbox（B1，B2，B3，B4，B5，......Bn）都选中
　　
　　　　救命呀。。
　　散分。。。。

[alan99]

<script language=javascript>
if (a.checked==true)
{
B1.checked=true;
}
</script>

这样不行吗?

[brightheroes]

<INPUT type="checkbox" onclick="selectall()" id = "ck0"></P>

<P><INPUT type="checkbox" id= "ck1"><INPUT type="checkbox" id="ck2"><INPUT type="checkbox" id="ck3"></P>
<script>
function selectall()
{
document.all.ck1.checked = document.all.ck0.checked;
document.all.ck2.checked =document.all.ck0.checked;
document.all.ck3.checked = document.all.ck0.checked;
}

</script>

[luaiping]

function checkboxclick()
{
if (document.getElementById("a").checked == true)
{
for (var i = 1;i <= 1;i++)
{
document.getElementById("B"+i).checked = true;
}
}
}

a.Attributes.Add("onclick","javascript:checkboxclick();");

[luaiping]

for (var i = 1;i <= 1;i++)
应该是i<=n

[rickjelly2004]

document.getElementById("checkboxid").checked = true

[adminyao]

<script language="javascript">
function selectall()
{
if (document.form1.check_a.checked==true)
{
for(var i=0;i<document.form1.test_rad.length;i++)
eval("document.form1.test_rad["+i+"]").checked=true;
}

}
</script>

[xzq686]

给你一个完整的。这个我一直在用。
//全部选中
<script language="javascript">
function checkall(){
if(document.getElementById("a").checked)
{
for(var i=0;i<document.getElementsByName("check_B").length;i++)
{
if(document.getElementsByName("check_B")[i].disabled==false)
document.getElementsByName("check_B")[i].checked=true;
}
}
else
{
for(var i=0;i<document.getElementsByName("check_B").length;i++)
{
if(document.getElementsByName("check_B")[i].disabled==false)
document.getElementsByName("check_B")[i].checked=false;
}
}
}
</script>

<input type="checkbox" name="a" value="1" ID="a" onclick="checkall()">
<input type="checkbox" name="check_B" value="1" ID="B1">
<input type="checkbox" name="check_B" value="1" ID="B2">
<input type="checkbox" name="check_B" value="1" ID="B3">

[活靶子哥哥]

用1个CheckBox或者按钮或者连接实现页面上的CheckBox全选功能

http://aspxboy.com/private/showthread.asp?threadid=244

[xjking0331]

<SCRIPT language="javascript">
function CheckAll()
{
var count = document.Form1.elements.length;
for (var i=0;i<count;i++)
{
var e = document.Form1.elements[i];
if (e.name != 'chkall' && e.type == 'checkbox')//其他'checkbox'的选择与否跟控制他们的'chkall' 的选择状态一致。
e.checked = document.Form1.chkall.checked;
}
}
SCRIPT>

[vzxq]

function SelectAll (chkVal,idvalue) {
//查找Forms里面所有的元素
for (var i=0; i<frm.elements.length; i++) {
var e=frm.elements[i];
if ((e.name != 'allbox') && (e.type=='checkbox')){
if(chkVal == true) {
e.checked=true;
}
else {
dL(e);
e.checked = false;
}

} //if
} //for
}

[goody9807]

function SelectAllCheck()
{
var m=window.document.Form1.elements.length;
for(var t=0;t<m;t++)
{
if(window.document.Form1.elements[t].name.indexOf("CheckBoxList1")!=-1)//找到
{
if(window.document.Form1.SelectAll.checked==true)
window.document.Form1.elements[t].checked=true;
else
window.document.Form1.elements[t].checked=false;
}

}
return false;
}
</script>
------------------------------------------------

[goody9807]

function CheckedCount()
{
try
{

var mm = document.getElementsByTagName("input").length ;
for(var i=0;i<mm;i++)
{
var dd = document.getElementsByTagName("input").item(i);
if(dd.type == "checkbox")
{

if(！dd.checked)
{
dd.checked = true;
}

}
}

}
catch(e)
{
//alert(e);
}
}

[delphi1998]

我是小许咧！

解决方法如下：
设置你的那个TreeView中某个节点的CheckBox=true;其结果就是你需要的前面带小框的效果。
然后把AutoPostBack=true,在生成树的事件中，判断一个节点是否被勾选，如果勾选，则把与它相同前缀ID的那个节点的CheckBox=true即可。并且注意在点击后与后台数据库要交互一次数据。

[myexam]

<ASP:DATAGRID id="myDataGrid" runat="server" AutoGenerateColumns="false" HeaderStyle-BackColor="#aaaadd"
Font-Size="8pt" Font-Name="Verdana" CellSpacing="0" CellPadding="3" ShowFooter="true" BorderColor="Black"
BackColor="AntiqueWhite" Width="600">
<HeaderStyle BackColor="NavajoWhite"></HeaderStyle>
<FooterStyle BackColor="NavajoWhite"></FooterStyle>
<Columns>
<asp:TemplateColumn HeaderText="contract">
<HeaderTemplate>
<input type="checkbox" id="checkAll" onclick="CheckAll(this);" runat="server" name="checkAll">
</HeaderTemplate>
<ItemTemplate>
<input type="checkbox" runat="server" id="EmpId" onclick="CheckChanged();" checked='false'
name="EmpId" />
</ItemTemplate>
</asp:TemplateColumn>
<asp:TemplateColumn HeaderText="EmployeeID">
<ItemTemplate>
<asp:Label id="Id" Text='<%#
DataBinder.Eval(Container.DataItem, "EmployeeID") %>' runat="server" />
</ItemTemplate>
</asp:TemplateColumn>
<asp:BoundColumn DataField="FirstName" HeaderText="FirstName"></asp:BoundColumn>
<asp:BoundColumn DataField="LastName" HeaderText="LastName"></asp:BoundColumn>
<asp:BoundColumn DataField="Title" HeaderText="Title"></asp:BoundColumn>
</Columns>
</ASP:DATAGRID>
<asp:Button id="ShowSl" runat="server" Text="Show Selection"></asp:Button>

---------------------------------------
Protected cnnDB As SqlConnection

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'在此处放置初始化页的用户代码
cnnDB = New SqlConnection("server=myx;user id=sa;password=myx;database=Northwind")

If Not IsPostBack Then
bindGrid()
End If

Dim strScript As String
strScript = "<script language=JavaScript> "
strScript += "function CheckAll(checkAllBox ) "
strScript += "{ "
strScript += " var frm = document.Form1; "
strScript += " var ChkState=checkAllBox.checked; "
strScript += " for(i=0;i< frm.length;i++) "
strScript += " { "
strScript += " e=frm.elements[i]; "
strScript += " if(e.type=='checkbox' && e.name.indexOf('Id') != -1)"
strScript += " e.checked= ChkState ; "
strScript += " } "
strScript += "} "
strScript += " </script> "
If Not IsClientScriptBlockRegistered("clientScriptCheckAll") Then
RegisterClientScriptBlock("clientScriptCheckAll", strScript)
End If

strScript = ""
strScript = "<script language=JavaScript> "
strScript += "function CheckChanged() "
strScript += "{ "
strScript += " var frm = document.Form1; "
strScript += " var boolAllChecked; "
strScript += " boolAllChecked=true; "
strScript += " for(i=0;i< frm.length;i++) "
strScript += " { "
strScript += " e=frm.elements[i]; "
strScript += " if ( e.type=='checkbox' && e.name.indexOf('Id') != -1 ) "
strScript += " if(e.checked== false) "
strScript += " { "
strScript += " boolAllChecked=false; "
strScript += " break; "
strScript += " } "
strScript += " } "
strScript += " for(i=0;i< frm.length;i++) "
strScript += " { "
strScript += " e=frm.elements[i]; "
strScript += " if ( e.type=='checkbox' && e.name.indexOf('checkAll') != -1 )"
strScript += " { "
strScript += " if( boolAllChecked==false) "
strScript += " e.checked= false ; "
strScript += " else "
strScript += " e.checked= true; "
strScript += " break; "
strScript += " } "
strScript += " } "
strScript += " } "
strScript += " </script> "
If Not IsClientScriptBlockRegistered("clientScriptCheckChanged") Then
RegisterClientScriptBlock("clientScriptCheckChanged", strScript)
End If

End Sub

Private Sub bindGrid()
Dim da As SqlDataAdapter = New SqlDataAdapter("select * from Employees", cnnDB)
Dim ds As DataSet = New DataSet
da.Fill(ds, "Employees")
myDataGrid.DataSource = ds.Tables("Employees").DefaultView
myDataGrid.DataBind()
End Sub


Private Sub ShowSl_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ShowSl.Click
For Each di As DataGridItem In myDataGrid.Items
Dim chkBx As HtmlInputCheckBox = di.FindControl("EmpId")
If chkBx.Checked = True Then
Dim lbl As Label = di.FindControl("Id")
Response.Write(lbl.TabIndex & "<br>")
End If
Next di
End Sub

演示地址:
http://myx.name/demo/ChkBoxInGrid/WebForm1.aspx

[hwmok]

<INPUT type="checkbox" onclick="selectall()" id = "ck0"></P>

<P><INPUT type="checkbox" id= "ck1"><INPUT type="checkbox" id="ck2"><INPUT type="checkbox" id="ck3"></P>
<script>
function selectall()
{
document.all.ck1.checked = document.all.ck0.checked;
document.all.ck2.checked =document.all.ck0.checked;
document.all.ck3.checked = document.all.ck0.checked;
}

</script>

这种方式比较方便