js为下拉列表赋值

function addItemmonth() {

var tOption = document.createElement("Option");

tOption.text = "月明显";

tOption.selected = true;

tOption.value = document.all("DropDownList3").options.length + 1;

document.all("DropDownList3").add(tOption);

}

function CallBack(data) {

var obj= document.getElementById("ab");

obj.length=0;

if (data.length>0) {

for(var i=0;i<data.length;i++)

{

obj.options[obj.length]=new Option(data[i]["foodname"],data[i]["foodname"]);

}

}else

{

obj.style.display="none";

obj.length=0;

}

}