javascript css styleFloat和cssFloat

LTFunction.setFloatStyle=function(obj,style) 
{ 
var sty=obj.style; 
if('cssFloat' in sty){ 
obj.style.cssFloat=style; 
}else if('styleFloat' in sty){ 
obj.style.styleFloat=style; 
}else{ 
throw 'set float style:'+style+'error.'; 
} 
}