Things change in the classic 'frontend' role so fast now that the top-level trends need to be conveyed to those in hiring positions more regularly. In my previous digital agency I moved from being a backend dev (C#) to being a bit of a hybrid, doing most of the JS work. The company was unaware this JS-focused role existed until I requested to fill it and even then I was just considered a frontend dev by most.

Fortunately there was an understanding between myself and the 2 other frontend guys that they were the CSS guys and I was the JS guy so we had a decent spread of skills and could use each other for advice if not pass work around.

There's now such a huge area of expertise in SVG, animation and 3D that it's another whole new role if there's enough work; it's voodoo to me as someone who is pretty nifty with JS and SCSS.