可以用更简单的方法就是使用addEventListener和事件冒泡然后在使用事件源元素获取每个span
buttons.addEventListener('click', function(e){var e = window.event || arguments[0];var src = e.target || e.srcElement;
var myIndex= parseInt(src.getAttribute('index'));var offset = -600 * (myIndex - index);animate(offset);index = myIndex;}, false)
buttons.addEventListener('click', function(e){var e = window.event || arguments[0];var src = e.target || e.srcElement;
var myIndex= parseInt(src.getAttribute('index'));var offset = -600 * (myIndex - index);animate(offset);index = myIndex;}, false)