I had the need to emit an HTML attribute today which contained a hyphen. Aside: a hyphen is the thing which joins two words while a dash is the thing which is used to denote a sentence interruption

Dash

The zombies are coming — I’m not afraid.

Hyphen

Zombies are flesh-eaters.

Both

The flesh-eating zombies are coming — I’m not afraid.

There are two different dashes too, but we’re already pretty far off track here — let’s reel it in.

There are actually an infinite number of valid HTML5 attributes which contain hyphens. You can write data-[anything] to add data to an arbitrary data to your elements. I find it to be very useful to have this standard for data attributes. If you’re using AngularJS then you’ll probably be making use of a lot of ng-* attributes. I came across some trouble when I was trying to emit this data from the HTML helper methods in ASP.net MVC. You can’t just do

@Html.TextAreaFor(x=>x.Name, new { data-age="fifteen"})

Because the hyphen is interpreted as a minus. Solving this is actually very easy. Razor will automatically replace underscores with hyphens so

@Html.TextAreaFor(x=>x.Name, new { data_age="fifteen"}) gets you what you want.