You will have to use jQuery. Check the below sample
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
DataTable dt = new DataTable();
dt.Columns.AddRange(new DataColumn[1] { new DataColumn("ImageUrl") });
dt.Rows.Add("http://www.aspforums.net/Avatars/Mudassar.jpg");
dt.Rows.Add("http://www.aspforums.net/Avatars/shivanand.jpg");
DataList1.DataSource = dt;
DataList1.DataBind();
}
}
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
<script type = "text/javascript">
$(function () {
var images = $("[id*=DataList1] [id*=Image1]");
for (var i = 0; i < images.length; i++) {
alert(images[0].src);
}
});
</script>
</head>
<body>
<form id="form1" runat="server">
<asp:DataList ID="DataList1" runat="server">
<ItemTemplate>
<asp:Image ID="Image1" runat="server" ImageUrl = '<%# Eval("ImageUrl") %>' />
</ItemTemplate>
</asp:DataList>
</form>
</body>
</html>
