<asp:CheckBox ID="CheckBox1" runat="server" Text="Select All" onclick="checkAll(this);" />
<br />
<asp:CheckBoxList ID="CheckBoxList1" runat="server">
    <asp:ListItem Value="Item 1">Item 1</asp:ListItem>
    <asp:ListItem Value="Item 2">Item 2</asp:ListItem>
    <asp:ListItem Value="Item 3">Item 3</asp:ListItem>
    <asp:ListItem Value="Item 4">Item 4</asp:ListItem>
    <asp:ListItem Value="Item 5">Item 5</asp:ListItem>
    <asp:ListItem Value="Item 6">Item 6</asp:ListItem>
</asp:CheckBoxList>

<script type="text/javascript">
    function checkAll(obj1) {
        var checkboxCollection = document.getElementById('<%=CheckBoxList1.ClientID %>').getElementsByTagName('input');

        for (var i = 0; i < checkboxCollection.length; i++) {
            if (checkboxCollection[i].type.toString().toLowerCase() == "checkbox") {
                checkboxCollection[i].checked = obj1.checked;
            }
        }
    }
</script>

当你调用document.getElementsByName("name")时，你会得到一个Object。使用.item(index)遍历Object的所有项

HTML:

<input type="checkbox" onclick="for(c in document.getElementsByName('rfile')) document.getElementsByName('rfile').item(c).checked = this.checked">

<input type=​"checkbox" name=​"rfile" value=​"/​cgi-bin/​">​
<input type=​"checkbox" name=​"rfile" value=​"/​includes/​">​
<input type=​"checkbox" name=​"rfile" value=​"/​misc/​">​
<input type=​"checkbox" name=​"rfile" value=​"/​modules/​">​
<input type=​"checkbox" name=​"rfile" value=​"/​profiles/​">​
<input type=​"checkbox" name=​"rfile" value=​"/​scripts/​">​
<input type=​"checkbox" name=​"rfile" value=​"/​sites/​">​
<input type=​"checkbox" name=​"rfile" value=​"/​stats/​">​
<input type=​"checkbox" name=​"rfile" value=​"/​themes/​">​

也许有点晚了，但是当处理“全部选中”复选框时，我相信您还应该处理当您选中“全部选中”复选框，然后取消选中下面的一个复选框时的场景。

在这种情况下，它应该自动取消勾选所有复选框。

此外，当手动选中所有复选框时，您应该最终自动选中所有复选框。

您需要两个事件处理程序，一个用于勾选全部框，另一个用于单击下面的任何单个框。

// HANDLES THE INDIVIDUAL CHECKBOX CLICKS
function client_onclick() {
    var selectAllChecked = $("#chk-clients-all").prop("checked");

    // IF CHECK ALL IS CHECKED, AND YOU'RE UNCHECKING AN INDIVIDUAL BOX, JUST UNCHECK THE CHECK ALL CHECKBOX.
    if (selectAllChecked && $(this).prop("checked") == false) {
        $("#chk-clients-all").prop("checked", false);
    } else { // OTHERWISE WE NEED TO LOOP THROUGH INDIVIDUAL CHECKBOXES AND SEE IF THEY ARE ALL CHECKED, THEN CHECK THE SELECT ALL CHECKBOX ACCORDINGLY.
        var allChecked = true;
        $(".client").each(function () {
            allChecked = $(this).prop("checked");
            if (!allChecked) {
                return false;
            }
        });
        $("#chk-clients-all").prop("checked", allChecked);
    }
}

// HANDLES THE TOP CHECK ALL CHECKBOX
function client_all_onclick() {
    $(".client").prop("checked", $(this).prop("checked"));
}

<script language="JavaScript">
function toggle(source) {
  checkboxes = document.getElementsByName('foo');
  for(var checkbox in checkboxes)
    checkbox.checked = source.checked;
}
</script>

<input type="checkbox" onClick="toggle(this)" /> Toggle All<br/>

<input type="checkbox" name="foo" value="bar1"> Bar 1<br/>
<input type="checkbox" name="foo" value="bar2"> Bar 2<br/>
<input type="checkbox" name="foo" value="bar3"> Bar 3<br/>
<input type="checkbox" name="foo" value="bar4"> Bar 4<br/>

更新:

对于每个…in construct似乎不能工作，至少在Safari 5或Chrome 5中是这样。这段代码应该在所有浏览器中工作:

function toggle(source) {
  checkboxes = document.getElementsByName('foo');
  for(var i=0, n=checkboxes.length;i<n;i++) {
    checkboxes[i].checked = source.checked;
  }
}

同一表单上可能有不同的复选框集。下面是一个通过类名选择/取消选择复选框的解决方案，使用普通javascript函数document.getElementsByClassName

全选按钮

<input type='checkbox' id='select_all_invoices' onclick="selectAll()"> Select All

要选择的一些复选框

<input type='checkbox' class='check_invoice' id='check_123' name='check_123' value='321' />
<input type='checkbox' class='check_invoice' id='check_456' name='check_456' value='852' />

javascript

    function selectAll() {
        var blnChecked = document.getElementById("select_all_invoices").checked;
        var check_invoices = document.getElementsByClassName("check_invoice");
        var intLength = check_invoices.length;
        for(var i = 0; i < intLength; i++) {
            var check_invoice = check_invoices[i];
            check_invoice.checked = blnChecked;
        }
    }

演示http://jsfiddle.net/H37cb/

<script type="text/javascript" src="http://code.jquery.com/jquery-latest.min.js" /></script>

<script type="text/javascript">
$(document).ready(function(){

$('input[name="all"],input[name="title"]').bind('click', function(){
var status = $(this).is(':checked');
$('input[type="checkbox"]', $(this).parent('li')).attr('checked', status);
});

});
</script>




<div id="wrapper">
 <li style="margin-top: 20px">
  <input type="checkbox" name="all" id="all" /> <label for='all'>All</label>
  <ul>
   <li><input type="checkbox" name="title" id="title_1" /> <label for="title_1"><strong>Title 01</strong></label>
    <ul>
     <li><input type="checkbox" name="selected[]" id="box_1" value="1" /> <label for="box_1">Sub Title 01</label></li>
     <li><input type="checkbox" name="selected[]" id="box_2" value="2" /> <label for="box_2">Sub Title 02</label></li>
     <li><input type="checkbox" name="selected[]" id="box_3" value="3" /> <label for="box_3">Sub Title 03</label></li>
     <li><input type="checkbox" name="selected[]" id="box_4" value="4" /> <label for="box_4">Sub Title 04</label></li>
    </ul>
   </li>
  </ul>
  <ul>
   <li><input type="checkbox" name="title" id="title_2" /> <label for="title_2"><strong>Title 02</strong></label>
    <ul>
     <li><input type="checkbox" name="selected[]" id="box_5" value="5" /> <label for="box_5">Sub Title 05</label></li>
     <li><input type="checkbox" name="selected[]" id="box_6" value="6" /> <label for="box_6">Sub Title 06</label></li>
     <li><input type="checkbox" name="selected[]" id="box_7" value="7" /> <label for="box_7">Sub Title 07</label></li>
    </ul>
   </li>
  </ul>
 </li>
</div>