<script type="text/javascript">

var ul = document.getElementById('ul');

var canvas = document.getElementById('canvas');

ul.addEventListener('click', function(e){

var that = e.target;

canvas.style.background = getStyle(that,'background');

});

//读取样式表数据

function getStyle(obj,name){

   return window.getComputedStyle?getComputedStyle(obj , null)[name]:obj.currentStyle[name]

}

</script>