java脚本提醒选择多个选项..in <select> HTMl标记。和标签。不在标签正文中</select>

Question

java脚本，用于警告所选的mutile选项..in <select> HTMl标记。和标签。不在<form>标签主体里面怎么做....

谢谢

Answer 1

var elem = document.getElementById("sel1").getElementsByTagName("option");
var len = elem.length;
var sel = new Array();

for(i=0; i<len;i++)
{
    if(elem[i].selected == true)
    {
        sel.push(elem[i].value);
    }   
}

alert(sel.join());

<强> Working demo