获取两个标签的id之后，怎么将这两个id拼在一起？

Question

我在获取两个标签的id（aId，bId）之后，想将这两个标签拼在一起，然后打印出来

    for(var i = 0;i<aLi.length;i++){
        aLi[i].onclick = function(){
            var aTxt = this.innerHTML;
             window.aId = this.id;
            document.getElementById('ss').innerHTML = aTxt;
        }
    }
    for(var j = 0;j<bLi.length;j++){
        bLi[j].onclick = function(){
            var bTxt = this.innerHTML;
             window.bId = this.id;
            document.getElementById('cc').innerHTML = bTxt;
        }
    }

 var    addId = aId + bId;
    var oBtn = document.getElementById('btn');
    oBtn.onclick = function(){
        alert(addId);
    }

这么写可以么？

Answer 1

   <p id="t1">第一题您选择的是<strong><u id="ss"></u></strong></p>
    <ul id="choose1">
        <li id="a1">哈哈</li>
        <li id="a2">呵呵</li>
        <li id="a3">嘿嘿</li>
        <li id="a4">吼吼</li>
    </ul>
    <p id="t2">第二题您选择的是<strong><u id="cc"></u></strong></p>
    <ul id="choose2">
        <li id="b1">java</li>
        <li id="b2">ios</li>
        <li id="b3">Android</li>
        <li id="b4">php</li>
        <li id="b5">jquery</li>
    </ul>
    <input type="button" id="btn" value="答案"/>
<script type="text/javascript">
    var addId, aId, bId;
    window.onload = function () {
        var aLi = document.getElementById('choose1').getElementsByTagName('li');
        var bLi = document.getElementById('choose2').getElementsByTagName('li');
        for (var i = 0; i < aLi.length; i++) {
            aLi[i].onclick = function () {
                var aTxt = this.innerHTML;
                aId = this.id;
                document.getElementById('ss').innerHTML = aTxt;
            }
        }
        for (var j = 0; j < bLi.length; j++) {
            bLi[j].onclick = function () {
                var bTxt = this.innerHTML;
                bId = this.id;
                document.getElementById('cc').innerHTML = bTxt;
            }
        }
    }

    var oBtn = document.getElementById('btn');
    oBtn.onclick = function () {
        addId = (aId || '') + (bId || '');
        alert(addId);
    }
</script>