var getStyle=function(){
var f=document.defaultView;
return new Function('el','style',[
"style.indexOf('-')>-1 && (style=style.replace(/-(\\w)/g,function(m,a){return a.toUpperCase()}));",
"style=='float' && (style='",
f ? 'cssFloat' : 'styleFloat',
"');return el.style[style] || ",
f ? 'window.getComputedStyle(el, null)[style]' : 'el.currentStyle[style]',
' || null;'].join(''));
}();
//使用示例：
var el=document.getElementById('test');
getStyle(el,'line-height');
getStyle(el,'color');
getStyle(el,'float');