Test if a browser supports VH. Based on the idea from vminpoly: https://github.com/saabi/vminpoly/blob/master/vminpoly.js

testvh.js

      supportsVh = function () {
        var detector = document.createElement('div'),
            winHeight = parseInt(window.innerHeight / 10, 10),
            testHeight;

        detector.style.height = '10vh'; // set an arbitrarily chosen height
        document.getElementsByTagName('body')[0].appendChild(detector); // add the element
        testHeight = parseInt(window.getComputedStyle(detector, null).height, 10); //get the computed style of the element

        document.getElementsByTagName('body')[0].removeChild(detector); // now remove the element
        return (testHeight === winHeight); //return whether the element's computed height and the window's height match
      }