<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>网页计算器</title>
</head>
<body>
<p>整数1：<input type="text" id="num1"></p>
<p>整数2：<input type="text" id="num2"></p>
<p>
<input type="button" value="相加" onclick="calc(add)">
<input type="button" value="相减" onclick="calc(sub)">
<input type="button" value="相乘" onclick="calc(mul)">
<input type="button" value="相除" onclick="calc(div)">
</p>
<p>结果：<input type="text" id="result" readonly></p>
</body>
</html>
<script>
function calc(func){
var result = document.getElementById(‘result‘);
var num1 = parseInt(document.getElementById(‘num1‘).value);
var num2 = parseInt(document.getElementById(‘num2‘).value);
if(isNaN(num1) || isNaN(num2)){
alert(‘请输入数字‘);
return false;
}
result.value = func(num1,num2);
}
function add(num1,num2){
return num1+num2;
}
function sub(num1,num2){
return num1-num2;
}
function mul(num1,num2){
return num1*num2;
}
function div(num1,num2){
if(num2===0){
alert(‘除数不能为零‘);
return ‘‘;
}
return num1/num2;
}
</script>
原文：https://www.cnblogs.com/xianggua/p/11121840.html