js获取所有复选框中的值

function next(openId){
var box = document.getElementsByName("box");
var objArray = box.length;
var chestr="";

for(var i=0;i<objArray;i++){
if(box[i].checked == true){
chestr+=box[i].value+",";
}
}
alert(chestr);
href = "${ctx }/fw/open?openId="+openId+"&chestr="+chestr;
window.showModalDialog( href,'window',"dialogHeight=600px;dialogWidth=910px;center=yes");
}

<input type="checkbox" name="box" id="box1" value="区划" />区划
<input type="checkbox" name="box" id="box2" value="邮编编码" />邮编编码
<input type="checkbox" name="box" id="box3" value="联系电话" />联系电话

......
<input type="button" name="button" id="button" onclick="checkbox()" value="下一步" />