javascriptはブラウザがCSS 3属性をサポートすると判断します.

function getsupportedprop(proparray){
    var root=document.documentElement; //reference root element of document
    for (var i=0; i<proparray.length; i++){ //loop through possible properties
        if (proparray[i] in root.style){ //if property exists on element (value will be string, empty string if not set)
            return proparray[i]; //return that string
        }
    }
}
var boxshadowprop=getsupportedprop([ 'OBoxShadow','WebkitTransform','MozTransform']);