function change() {
var a = document.getElmentById("a");
var b = document.getElmentById("b").value;
var c = document.getElmentById("c").value;
c.value = parseInt(b)- parseInt(c);
}
从onchange里调用这个。
var a = document.getElmentById("a");
var b = document.getElmentById("b").value;
var c = document.getElmentById("c").value;
c.value = parseInt(b)- parseInt(c);
}
从onchange里调用这个。
<input id="txtb" onkeyup="txtSub.value=txta.value-this.value">
<input id="txtSub">
<head>
<script type="text/javascript">
function change() {
var a = document.getElementById("a").value
var b = document.getElementById("b").value;
var c = document.getElementById("c");
if (a == "" || b == "") return;
c.value = parseInt(b) - parseInt(a);
}
</script>
</head>
<body>
a<input id="a" onchange="javascript:change();" /><br />
b<input id="b" onchange="javascript:change();" /><br />
c<input id="c" />
</body>
</html>
对不起。。刚写错了。。