How can I use the script defer attribute for ASP MVC 4 Bundles with Scripts.Render

Try upgrading the Web Optimization to version 1.1.0 onCodeplex Site or via Nuget Package

In version 1.1.0 they included Element Template Strings.So if you want a script tag to contains the defer attribute you can easily do this:

@Scripts.RenderFormat("<script src='{0}' defer></script>","~/bundles/jquery")

and the following markup will be generated:

<script src="/Scripts/jquery-1.7.1.js" defer></script> 

The answer above is great. I just want to quickly paste my code over here for those who wants to have a more concise syntax.

Add a new C# class

// --------------------------------------------------------------------------------------------------------------------// <copyright file="Scripts7.cs" company="Believe">//   http://believeblog.azurewebsites.net/// </copyright>// --------------------------------------------------------------------------------------------------------------------using System.Web;using System.Web.Optimization;namespace MVCExtension{    /// <summary>    ///     The scripts.    /// </summary>    public static class Scripts    {        /// <summary>        /// Render scripts as deferred        /// </summary>        /// <param name="paths">        /// The paths.        /// </param>        /// <returns>        /// The <see cref="IHtmlString"/>.        /// </returns>        public static IHtmlString RenderDefer(params string[] paths)        {            return Scripts.RenderFormat(@"<script src='{0}' defer></script>", paths);        }    }}

Then, use Razor syntax:

@Scripts.RenderDefer("~/bundles/jquery")

Or Webform syntax:

<%: Scripts.RenderDefer("~/bundles/jquery") %>

You can use BundleTable.Bundles.ResolveBundleUrl :

<script src="@(BundleTable.Bundles.ResolveBundleUrl("~/bundles/jquery"))" defer></script>