关于setAttribute的问题
<div class="food" id="herd">
</div>
<h1 onclick="hattr()">trjtr</h1>
<script>
function hattr(){
var anode=document.getElementsByClassName("food");
anode[0].setAttribute("id","987");
anode[0].setAttribute("class","789");
}为什么 anode[0] 就没有问题；而 anode 就不正确了
