function checkbox(checknames) { var newstr=document.getElementsByName(checknames); var objarray=newstr.length; var chestr=""; for (nubi=0;nubi<objarray;nubi++) { if(newstr[nubi].checked == true) { chestr+=newstr[nubi].value+","; } } if(chestr == "") { alert("请先选择一个选项!"); } else { return chestr; } }