JS_實現一個簡易計算器

Pop_Rain發表於2017-07-07
JS
<!DOCTYPE html>
<html>
<head>
<title>14th_test</title>
<meta charset="gb2312">
</head>

<body>
<h1>這是一個標題</h1>
<p>以下是一個簡易計算器</p>

<table border="1" style="position:center;">
<tr>
<th>第一個數</th>
<td><input id="fir" type="text" /></td>
</tr>

<tr>
<th>第二個數</th>
<td><input id="sec" type="text" /></td>
</tr>

<tr>
<td colspan="2">
<button type="button" onclick="add()">+</button>
<button type="button" onclick="substract()">-</button>
<button type="button" onclick="multiply()">*</button>
<button type="button" onclick="divide()">/</button>
</td>
</tr>

<tr>
<td colspan="2"><p id="result"></p></td>
</tr>
</table>

<script>
var res; //儲存計算結果
function add()
{
var first = document.getElementById("fir").value;
var second = document.getElementById("sec").value;
	res = Number(first) + Number(second);   //這裡"+"兩端必須Number型別轉換，否則當成字串連線
	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:


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