<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>test</title>
<script type="text/javascript" src='http://code.jquery.com/jquery-1.11.0-beta1.js'></script>
</head>
<body> <select onchange="price()" id="price">
<option value="0" selected>选择价格</option>
<option value="10">10</option>
<option value="20">20</option>
<option value="30">30</option>
<option value="40">40</option>
</select>
<select onchange="count()" id="num">
<option value="0" selected>选择数量</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>
<input id="cout" type="text" />
<script type="text/javascript">
function price(){
var price = $("#price").val();
$("#cout").val(price);
}
function count(){
console.log($("#num").val()*$("#price").val())
$("#cout").val($("#num").val()*$("#price").val());
}
</script>
</body>
</html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>test</title>
<script type="text/javascript" src='http://code.jquery.com/jquery-1.11.0-beta1.js'></script>
</head>
<body> <select onchange="price()" id="price">
<option value="0" selected>选择价格</option>
<option value="10">10</option>
<option value="20">20</option>
<option value="30">30</option>
<option value="40">40</option>
</select>
<select onchange="count()" id="num">
<option value="0" selected>选择数量</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>
<input id="cout" type="text" />
<script type="text/javascript">
function price(){
var price = $("#price").val();
$("#cout").val(price);
}
function count(){
console.log($("#num").val()*$("#price").val())
$("#cout").val($("#num").val()*$("#price").val());
}
</script>
</body>
</html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title></head>
<body>
<select onchange="price(this)" id="price">
<option value="0" selected>选择价格</option>
<option value="10">10</option>
<option value="20">20</option>
<option value="30">30</option>
<option value="40">40</option>
</select>
<select onchange="count(this)" id="num" disabled = "true">
<option value="0" selected>选择数量</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>
<input id="cout" type="text" />
<script>
var org=0;
function $(id){
return document.getElementById(id);
}
function price(obj){
var si = obj.selectedIndex;
if(si==0){
$('num').disabled = true;
$('cout').value = '';
return;
}else{
$('num').disabled = false;
$('num').selectedIndex = 0;
org = 0;
$('cout').value = obj.options[si].value;
return;
}
}
function count(obj){
var si = obj.selectedIndex;
if(si!==0){
if (org ===0 ){
org = $('cout').value;
}
var num = obj.options[si].value;
$('cout').value =org*num;
}
}
</script>
</body>
</html>
<option value="1" selected>选择价格</option>
<option value="10">10</option>
<option value="20">20</option>
<option value="30">30</option>
<option value="40">40</option>
</select>
<select name="num" id="num">
<option value="1" selected>选择数量</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
</select>
<input id="Payment" name="Payment" type="text" />
<script type="text/javascript">
/*越小的项目越容易粗心大意,下拉框哪个先选择都有可能,或者是反复选择*/
function Gid(id){return document.getElementById(id)}
var Activity = Gid("Activity"),num = Gid("num"),Payment = Gid("Payment");
Activity.onchange = num.onchange = function(){
var i = Activity.options[Activity.options.selectedIndex].value * num.options[num.options.selectedIndex].value;
Payment.value = i>1?i:"";
};
</script>