初学javascript 循环语句的写法。

Question

下面这段代码是判断当id="a1"的标签里面 没有内容是，样式为display:none; 一条可以这样写，但是几十条呢？这个id="a1"~id="a10"这个该怎么写呢？

 <div class="new_answer" id="a1"></div>
<script>
if(document.getElementById("a1").innerHTML==="")
document.getElementById("a1").style.display="none";
</script> 

如果有几十条呢？不可能写10条js代码吧？应该有循环写法的。初学不懂，请大神指点。

<div class="new_answer" id="a1"></div>
<div class="new_answer" id="a2"></div>
<div class="new_answer" id="a3"></div>
<div class="new_answer" id="a4"></div>
<div class="new_answer" id="a5"></div>
<div class="new_answer" id="a6"></div>
<div class="new_answer" id="a7"></div>
<div class="new_answer" id="a8"></div>
<div class="new_answer" id="a9"></div>
<div class="new_answer" id="a10"></div>

<script>
if(document.getElementById("a1").innerHTML==="")
document.getElementById("a1").style.display="none";
if(document.getElementById("a2").innerHTML==="")
document.getElementById("a2").style.display="none";
if(document.getElementById("a3").innerHTML==="")
document.getElementById("a3").style.display="none";
if(document.getElementById("a4").innerHTML==="")
document.getElementById("a4").style.display="none";
if(document.getElementById("a5").innerHTML==="")
document.getElementById("a5").style.display="none";
</script> 

Answer 1

 <div class="new_answer" id="a1"></div>
<div class="new_answer" id="a2"></div>
<div class="new_answer" id="a3"></div>
<div class="new_answer" id="a4"></div>
<div class="new_answer" id="a5"></div>
<div class="new_answer" id="a6"></div>
<div class="new_answer" id="a7"></div>
<div class="new_answer" id="a8">333</div>
<div class="new_answer" id="a9">222</div>
<div class="new_answer" id="a10">111</div>

<script type="text/javascript">
var paras = document.getElementsByTagName("div");
for ( var i=0;i<paras.length;i++ ) {
if (paras[i].getAttribute("class") == "new_answer" && paras[i].innerHTML==="")
paras[i].style.display="none";
}
</script>