用JS方法给元素加入CSS，还可以自动判断当前浏览器所适合的属性

看到一个国外的例子中有这样的helper function

    var pfx = (function () {
        var style = document.createElement('dummy').style,
            prefixes = 'Webkit Moz O ms Khtml'.split(' '),
            memory = {};
        return function ( prop ) {
            if ( typeof memory[ prop ] === "undefined" ) {

                var ucProp  = prop.charAt(0).toUpperCase() + prop.substr(1),
                    props   = (prop + ' ' + prefixes.join(ucProp + ' ') + ucProp).split(' ');
                
                memory[ prop ] = null;
                for ( var i in props ) {
                //判断浏览器中是否有这个属性，有的话则添加
                    if ( style[ props[i] ] !== undefined ) {
                        memory[ prop ] = props[i];
                        break;
                    }
                }

            }
            return memory[ prop ];
        }
    })();

    var css = function ( el, props ) {
        var key, pkey;
        for ( key in props ) {
            if ( props.hasOwnProperty(key) ) {
                pkey = pfx(key);
                if ( pkey != null ) {
                    el.style[pkey] = props[key];
                }
            }
        }
        return el;
    }
    var translate = function ( t ) {
        return " translate3d(" + t.x + "px," + t.y + "px," + t.z + "px) ";
    };
    
    var rotate = function ( r, revert ) {
        var rX = " rotateX(" + r.x + "deg) ",
            rY = " rotateY(" + r.y + "deg) ",
            rZ = " rotateZ(" + r.z + "deg) ";
        
        return revert ? rZ+rY+rX : rX+rY+rZ;
    };
    
    var scale = function ( s ) {
        return " scale(" + s + ") ";
    };

pfx方法主要是帮助判断添加适合的浏览器前缀，比如：

            css(el, {
                position: "absolute",
                transform: "translate(-50%,-50%)" +
                           translate(step.translate) +
                           rotate(step.rotate) +
                           scale(step.scale),
                transformStyle: "preserve-3d"
            });

调用结果后，el元素会加入css属性position, WebkitTransform,WebkitTransformStyle属性，这个是在chrome下，如果是在FireFox下，肯定是Moz开头的，相当有用的工具啊！