Vendor prefix detection

gistfile1.js

(function() {
    // Following spec is to expose vendor-specific style properties as:
    //   elem.style.WebkitBorderRadius
    // and the following would be incorrect:
    //   elem.style.webkitBorderRadius
    
    // Webkit ghosts their properties in lowercase but Opera & Moz do not.
    // Microsoft foregoes prefixes entirely <= IE8, but appears to
    //   use a lowercase `ms` instead of the correct `Ms` in IE9
    
    // More here: http://github.com/Modernizr/Modernizr/issues/issue/21
    var domPrefixes = ['Webkit', 'Moz', 'O', 'ms', 'Khtml'],
        style = document.createElement('div').style,
        pref;
    
    function getProp(prop) {
        var upperProp = prop.charAt(0).toUpperCase() + prop.slice(1);
        if (pref === undefined) {
            pref = null;
            for (var i = 0, len = domPrefixes.length; i < len; i++) {
                if ((domPrefixes[i] + upperProp) in style) {
                    pref = domPrefixes[i];
                    break;
                }
            }
        }
        if (prop in style)
            return prop;
        return pref ? pref + upperProp : undefined;
    }
    
    this.caps = {
        transition: getProp('transition'),
        transitionEnd: getProp('transitionEnd')
    };
})();