Add HTML helper methods for rendering globbed stylesheet & JavaScript references with fallback

[DamianEdwards]

Add methods to IHtmlHelper that support rendering HTML for stylesheet links and script blocks with support for globbed file paths and fallbacks. Basically the equivalent of the features of the link and script tag helpers.

Example

@section head {
    @if (HostingEnvironment.IsDevelopment()) {
        @Html.Stylesheet(include: "lib/**/*.css", exclude: "css/**/*.css");
        @Html.Stylesheet(include: "css/**/*.css", exclude: "lib/**/*.css");
    }
    else if (HostingEnvironment.IsProduction()) {
        @Html.Stylesheet(
            href: "//mycdn.com/bootstrap/2.1.0.min.css",
            fallbackHrefInclude: "lib/bootstrap/css/*.min.css",
            fallbackTestClass: "hidden", 
            fallbackTestProperty: "visibility",
            fallbackTestValue: "hidden");
        @Html.Stylesheet(href: "css/site.min.css", fallbackHrefInclude: "css/**/*.min.css");
    }
}

@section scripts {
    @if (HostingEnvironment.IsDevelopment()) {
        @Html.Script(src: "lib/jquery/jquery.js");
        @Html.Script(src: "lib/jquery-ui/jquery-ui.js");
        @Html.Script(include: "js/**/*.js", exclude: "lib/**/*.js");
    }
    else if (HostingEnvironment.IsProduction()) {
        @Html.Script(
            src: "//mycdn/jquery/2.1.2.min.js",
            fallbackSrc: "lib/jquery/jquery.min.js",
            fallbackTest: "window.jQuery"
        );
        @Html.Script(
            src: "//mycdn/jquery-ui/1.12.0.min.js",
            fallbackSrc: "lib/jquery-ui/jquery-ui.min.js",
            fallbackTest: "window.jQuery && window.jQuery.ui"
        );
        @Html.Script(src: "js/site.min.js" fallbackSrcInclude: "js/**/*.min.js");
    }
}

[Eilon]

I think that if you do this you need to have a firm answer on how they will be sorted.

[Eilon]

We have some logic in Bundling & Optimization but before grabbing code we should figure out what we want.

[DamianEdwards]

@Eilon they'd be sorted as they're found on disk, hence the example above explicitly added libs first. This is essentially a straight port of what we have for the script & link tag helpers.

[Eilon]

What does "as found on disk" mean? As far as I know the file system APIs on Windows don't make any guarantees at all. Not sure about *nix / Mac OS.

[rynowak]

@DamianEdwards - do you still want to do this? Or do we want to divest from adding more to HTML helpers?

[DamianEdwards]

Nobody has asked for this.