How can we enable data annotation validation on client side?

It’s a two-step process: first reference the necessary jQuery files.

<script src="<%= Url.Content("~/Scripts/jquery-1.5.1.js") %>" type="text/javascript"></script>

<script src="<%= Url.Content("~/Scripts/jquery.validate.js") %>" type="text/javascript"></script>

<script src="<%= Url.Content("~/Scripts/jquery.validate.unobtrusive.js") %>" type="text/javascript"></script>

The second step is to call the EnableClientValidation method.

<% Html.EnableClientValidation(); %>