<script type="text/javascript">
function operate(){
var x = document.getElementById('x').value;
var y = document.getElementById('y').value;
var operator = document.getElementById('operator').value;
if((x != '') && (y != '')) {
if(operator == "+") {
alert(+x + +y);
} else if(operator == "-") {
alert(+x - +y);
} else if(operator == "*") {
alert(+x * +y);
}else if(operator == "/") {
alert(+x / +y);
}else if(operator == "%") {
alert(+x % +y);
}
}
else {
alert("Please Fill All Fields With Proper Value");
}
}
</script>
<input type='text' id='x' />
<select name="operator" id="operator">
<option value="+">+</option>
<option value="-">-</option>
<option value="*">*</option>
<option value="/">/</option>
<option value="%">%</option>
</select>
<input type='text' id='y' />
<input type='button' onclick='operate()' value='GO' />
