算数器联系

<input type="text" name="avalue" size="5" id="a" />

<select name="" id="d"><option >-</option><option >+</option><option >*</option><option >/</option></select>

<input type="text" name="bvalue" size="5" id="b" />=

<input type="button" value="计算" onclick="yunsuan()" />

<input type="text" readonly name="cvalue" size="5" id="c" />

<script language="javascript">

function yunsuan() {

var x, y, z; x=document.getElementById("a").

value; y=document.getElementById("b").

value; s=document.getElementById("d").value z=x+s+y;

if(isNaN(+x)||isNaN(+y)){ alert("shuzi"); return; } var c=eval(z); document.getElementById("c").value=c; }

</script>