<!DOCTYPE html>
<html>
<head>
<title>14th_test</title>
<meta charset="gb2312">
</head>
<body>
<h1>这是一个标题</h1>
<p>以下是一个简易计算器</p>
<table border="1" style="position:center;">
<tr>
<th>第一个数</th>
<td><input id="fir" type="text" /></td>
</tr>
<tr>
<th>第二个数</th>
<td><input id="sec" type="text" /></td>
</tr>
<tr>
<td colspan="2">
<button type="button" οnclick="add()">+</button>
<button type="button" οnclick="substract()">-</button>
<button type="button" οnclick="multiply()">*</button>
<button type="button" οnclick="divide()">/</button>
</td>
</tr>
<tr>
<td colspan="2"><p id="result"></p></td>
</tr>
</table>
<script>
var res; //保存计算结果
function add()
{
var first = document.getElementById("fir").value;
var second = document.getElementById("sec").value;
res = Number(first) + Number(second); //这里"+"两端必须Number类型转换，否则当成字符串连接
sent(res);
}
function substract()
{
var first = document.getElementById("fir").value;
var second = document.getElementById("sec").value;
res = first - second;
sent(res);
}
function multiply()
{
var first = document.getElementById("fir").value;
var second = document.getElementById("sec").value;
res = first * second;
sent(res);
}
function divide()
{
var first = document.getElementById("fir").value;
var second = document.getElementById("sec").value;
res = first / second;
sent(res);
}
function sent(re)
{
document.getElementById("result").innerHTML = re;
}
</script>
</body>
</html>output:
