JavaScript简单判断复选框是否选中及取出值的方法

<title>JavaScript 获取复选框的值</title>
<script>
function checkbox()
{
var str=document.getElementsByName("box");
var objarray=str.length;
var chestr="";
for (i=0;i<objarray;i++)
{
 if(str[i].checked == true)
 {
  chestr+=str[i].value+",";
 }
}
if(chestr == "")
{
 alert("请先选择复选框～！");
}
else
{
 alert("复选框的值是"+chestr);
}
}
</script>
选择您的拿手技术
<input type="checkbox" name="box" id="box1" value="ASP" />ASP
<input type="checkbox" name="box" id="box2" value="PHP" />PHP
<input type="checkbox" name="box" id="box3" value="JSP" />JSP
<input type="button" name="button" id="button" onclick="checkbox()" value="提交" />