The question regarding how to check/uncheck CheckBoxes within a GridView control using JavaScript has been asked many times. Here is a quick reference you can follow.
First we have the .aspx markup.
<script type="text/javascript">
function SelectAll(id) {
var frm = document.forms[0];
for (i=0;i<frm.elements.length;i++) {
if (frm.elements[i].type == "checkbox") {
frm.elements[i].checked = document.getElementById(id).checked;
}
}
}
</script>
<!-- assuming that SqlDataSource1 is the datasource for my GridView -->
<asp:GridView ID="GridView1" runat="server" DataSourceID="SqlDataSource1" Width="400px">
<Columns>
<asp:TemplateField>
<AlternatingItemTemplate>
<asp:CheckBox ID="CheckBox1" runat="server" />
</AlternatingItemTemplate>
<ItemTemplate>
<asp:CheckBox ID="CheckBox1" runat="server" />
</ItemTemplate>
<HeaderTemplate>
<asp:CheckBox ID="cbSelectAll" runat="server" Text="Select All" />
</HeaderTemplate>
<HeaderStyle HorizontalAlign="Left" />
<ItemStyle HorizontalAlign="Left" />
</asp:TemplateField>
</Columns>
</asp:GridView>
Next we have the code-behind in both VB and C#
VB
Protected Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GridView1.RowDataBound
If (e.Row.RowType = DataControlRowType.Header) Then
'adding an attribute for onclick event on the check box in the header
'and passing the ClientID of the Select All checkbox
DirectCast(e.Row.FindControl("cbSelectAll"), CheckBox).Attributes.Add("onclick", "javascript:SelectAll('" & _
DirectCast(e.Row.FindControl("cbSelectAll"), CheckBox).ClientID & "')")
End If
End Sub
C#
protected void GridView1_RowDataBound(object sender, System.Web.UI.WebControls.GridViewRowEventArgs e) {
if (e.Row.RowType == DataControlRowType.Header) {
//adding an attribute for onclick event on the check box in the header
//and passing the ClientID of the Select All checkbox
((CheckBox)e.Row.FindControl("cbSelectAll")).Attributes.Add("onclick", "javascript:SelectAll('" + ((CheckBox)e.Row.FindControl("cbSelectAll")).ClientID + "')");
}
}
The example above is fantastic, but there are a couple things that could be improved.
- The JavaScript Pseudo Protocol (Javascript:your method here) should be avoided, it's a fragment from the old Netscape days. Today there are better alternatives
- In this case we probably don't need the server-side portion altogether.
An excerpt about the JavaScript Pseudo Protocol:
"The javascript: pseudo-protocol should not be used in event handlers like onclick. It should only be used in attributes that contain a URL, for example in the href attribute of <a> elements and the action attribute of <form> elements. You can also use it to make bookmarlets." - Common JavaScript Mistakes
Another solution the .aspx markup:
<script type="text/javascript">
// Let's use a lowercase function name to keep with JavaScript conventions
function selectAll(invoker) {
// Since ASP.NET checkboxes are really HTML input elements
// let's get all the inputs
var inputElements = document.getElementsByTagName('input');
for (var i = 0 ; i < inputElements.length ; i++) {
var myElement = inputElements[i];
// Filter through the input types looking for checkboxes
if (myElement.type === "checkbox") {
// Use the invoker (our calling element) as the reference
// for our checkbox status
myElement.checked = invoker.checked;
}
}
}
</script>
<!-- assuming that SqlDataSource1 is the datasource for my GridView -->
<asp:GridView ID="GridView1" runat="server" DataSourceID="SqlDataSource1">
<Columns>
<asp:TemplateField>
<AlternatingItemTemplate>
<asp:CheckBox ID="CheckBox1" runat="server" />
</AlternatingItemTemplate>
<ItemTemplate>
<asp:CheckBox ID="CheckBox1" runat="server" />
</ItemTemplate>
<HeaderTemplate>
<asp:CheckBox ID="cbSelectAll" runat="server" Text="Select All" OnClick="selectAll(this)" />
</HeaderTemplate>
<HeaderStyle HorizontalAlign="Left" />
<ItemStyle HorizontalAlign="Left" />
</asp:TemplateField>
</Columns>
</asp:GridView>
