<!DOCTYPE html>
<meta charset="UTF-8">
<title>计算器
<script type="text/javascript">
window.onload =function() {
var otxt1 =document.getElementById('text1');
var otxt2 =document.getElementById('text2');
var obtn =document.getElementById('btn');
obtn.onclick =function() {
var sum =parseInt(otxt1.value) +parseInt(otxt2.value);
if(isNaN(sum)) {
alert('您输入的有误');
}else {
alert(sum);
}
}
}
<input type="text" id="text1" value="" />
<label>+
<input type="text" id="text2" value="" />
<input type="button" name="" id="btn" value="计算" />
</html>
