javascript操作select下拉列表框的一点小经验_表单特效

function changebrand1(oTextbox)
{
var brandTag=document.getElementById("ddlistSecondConsumeBrand");
var brand1=document.getElementById("txtbrand1");
var brand2=document.getElementById("txtbrand2");
var brandcolls=brandTag.options;
var textvalue=oTextbox.value;
var flag=0;
if(textvalue.length==0)
{
flag=1;
}
else if(textvalue.length>0)
{
for(var i=0;i{
if(oTextbox==brand1 && brandcolls[i].text==textvalue)
{
document.getElementById("ddlistFirstConsumeBrand").options.selectedIndex=i-1;
flag=1;
ChangeBrand(document.getElementById("ddlistFirstConsumeBrand"));
}
else if(oTextbox==brand2 && brandcolls[i].text==textvalue)
{
brandTag.selectedIndex=i;
flag=1;
ChangeBrand(brandTag);
}
}

if(flag==0)
{
alert("输入品牌错误！");
oTextbox.value="";
oTextbox.focus();
}
}
}

function ChangeBrand(me){
var brand1ID = document.all.ddlistFirstConsumeBrand.value;
var brand2ID = document.all.ddlistSecondConsumeBrand.value;
var brandvalue1=document.getElementById("txtbrand1");
var brandvalue2=document.getElementById("txtbrand2");
if((brand1ID=="10")&&(brand2ID=="-1"))
{
document.all.ddlistMilkPeriod.value=9;
}

for(var i=0;i{
if(document.getElementById("ddlistFirstConsumeBrand") == me && document.all.ddlistFirstConsumeBrand.selectedIndex==i)
{
brandvalue1.value=document.getElementById("ddlistFirstConsumeBrand").options[i].text;
}
if(document.getElementById("ddlistSecondConsumeBrand") == me && document.all.ddlistSecondConsumeBrand.selectedIndex==i)
{
brandvalue2.value=document.getElementById("ddlistSecondConsumeBrand").options[i].text;
}

if(i<8 && document.getElementById("ddlistFirstConsumeBrand") == me && document.all.ddlistFirstConsumeBrand.selectedIndex==i)
{
document.all.dv1.style.display="block";
document.all.dv2.style.display="none";
document.all.dv3.style.display="none";
document.getElementById("ddlistPotential").options[0].selected="selected";
break;
}
else if(i>0 && i<9 && document.getElementById("ddlistSecondConsumeBrand") == me && document.all.ddlistSecondConsumeBrand.selectedIndex==i)
{
document.all.dv1.style.display="block";
document.all.dv2.style.display="none";
document.all.dv3.style.display="none";
document.getElementById("ddlistPotential").options[0].selected="selected";
break;
}
else if(i>8)
{
document.all.dv1.style.display="none";
document.all.dv2.style.display="block";
document.all.dv3.style.display="block";
document.getElementById("ddlistPotential").options[1].selected="selected";
}
}
}