如何使用javascript设置CSS（我无权访问CSS文件）？

#fade div {
  -webkit-transition: opacity 1s;
  -moz-transition: opacity 1s;
  -o-transition: opacity 1s;
  -ms-transition: opacity 1s;       
  transition: opacity 1s;
  opacity: 0;
  position: absolute;
  height: 500px;
  width: 960px;
}

例如：

document.getElementById('fade').HOW-TO-TYPE-webkit-transition = 'opacity 1s';