摘要
前端計算器的編寫方法有很多插件可以完成，本文通過html+css+javascript原生方法編寫一款計算器，效果截圖如下：
本文主要用到的是JavaScript中的Math對象，對計算結果未做深入考究，僅探索一種實現思路。
<html>
<head>
<script language="JavaScript">
<!-- Begin
function doit() {
form.input.value = eval(form.input.value)
}
function Cos() {
x = form.input.value
if (x == '') alert('Error: Input Required');
else form.input.value = Math.cos(x);
}
function Sin() {
x = form.input.value
if (x == '') alert('Error: Input Required');
else form.input.value = Math.sin(x);
}
function Ln() {
x = form.input.value
if (x == '') alert('Error: Input Required');
else form.input.value = Math.log(x);
}
function Root() {
x = form.input.value
if (x == '') alert('Error: Input Required');
else form.input.value = Math.sqrt(x);
}
function Tan() {
x = form.input.value
if (x == '') alert('Error: Input Required');
else form.input.value = Math.tan(x);
}
function Icos() {
x = form.input.value
if (x == '') alert('Error: Input Required');
else form.input.value = Math.acos(x);
}
function Isin() {
x = form.input.value
if (x == '') alert('Error: Input Required');
else form.input.value = Math.asin(x);
}
function Itan() {
x = form.input.value
if (x == '') alert('Error: Input Required');
else form.input.value = Math.atan(x);
}
function Round() {
x = form.input.value
if (x == '') alert('Error: Input Required');
else form.input.value = Math.round(x);
}
function Ran() {
x = form.input.value
form.input.value = Math.random(x);
}
function Neg () {
x = form.input.value
if (x == '') alert('Error: Input Required');
else x = parseFloat(x) * -1;
}
function del() {
x = form.input.value
x = (x.substring) - 1
}
// End -->
</script>
<title>計算器</title>
<meta http-equiv="Content-Type" content="text/html; charset=big5" />
</head>
<body onload="document.form.input.focus()">
<div align="center">
<form name="form" method="post" action="javascript:doit()">
<table width="260" border="0" height="260" align="center" bordercolor="#0000FF" bgcolor="#0000FF">
<tbody>
<tr bgcolor="#FF0000">
<td colspan="7" height="2">
<div align="center">
<b><font face="Arial, Helvetica, sans-serif" color="#FFFFFF">科學計算器</font></b>
</div> </td>
</tr>
<tr bgcolor="#00FFFF">
<td colspan="7" height="2">
<div align="center">
<input type="text" name="input" size="40" />
</div> </td>
</tr>
<tr bgcolor="#000000">
<td width="50" height="4"> <input type="button" name="one" value="1" onclick="form.input.value += '1'" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #666666; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="4"> <input type="button" name="two" value="2" onclick="form.input.value += '2'" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #666666; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="4"> <input type="button" name="three" value="3" onclick="form.input.value += '3'" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #666666; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="20" height="4"> </td>
<td width="50" height="4"> <input type="button" name="clear" value="C" onclick="form.input.value = ''" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #9F0004; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="4"> <input type="button" name="percent" value=" % " onclick="form.input.value = eval(form.input.value) / 100" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="4"> <input type="button" name="(" value=" ( " onclick="form.input.value += '('" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
</tr>
<tr bgcolor="#000000">
<td width="50" height="2"> <input type="button" name="four" value="4" onclick="form.input.value += '4'" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #666666; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="2"> <input type="button" name="five" value="5" onclick="form.input.value += '5'" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #666666; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="2"> <input type="button" name="six" value="6" onclick="form.input.value += '6'" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #666666; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="20" height="2"> </td>
<td width="50" height="2"> <input type="button" name="times" value=" x " onclick="form.input.value += ' * '" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="2"> <input type="button" name="div" value=" / " onclick="form.input.value += ' / '" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="2"> <input type="button" name=")" value=" ) " onclick="form.input.value += ')'" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
</tr>
<tr bgcolor="#000000">
<td width="50" height="2"> <input type="button" name="seven" value="7" onclick="form.input.value += '7'" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #666666; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="2"> <input type="button" name="eight" value="8" onclick="form.input.value += '8'" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #666666; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="2"> <input type="button" name="nine" value="9" onclick="form.input.value += '9'" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #666666; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="20" height="2"> </td>
<td width="50" height="2"> <input type="button" name="plus" value=" + " onclick="form.input.value += ' + '" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="2"> <input type="button" name="minus" value=" - " onclick="form.input.value += ' - '" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="2"> <input type="button" name="round" value="Rnd" onclick="Round()" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
</tr>
<tr bgcolor="#000000">
<td width="50" height="2"> <input type="button" name="zero" value="0" onclick="form.input.value += '0'" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #666666; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="2"> <input type="button" name="point" value="." onclick="form.input.value += '.'" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #666666; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="2"> <input type="button" name="pi" value="PI" onclick="form.input.value += '3.1415926535897932384626433832795'" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #666666; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="20" height="2"> </td>
<td width="50" height="2"> <input type="button" name="pi2" value="+/-" onclick="Neg()" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="2"> <input type="button" name="DoIt" value=" = " onclick="doit()" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #9F0004; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50" height="2"> <input type="button" name="round2" value="Ran#" onclick="Ran()" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
</tr>
<tr bgcolor="#0000FF">
<td width="50" height="24"> </td>
<td width="50" height="24"> </td>
<td width="50" height="24"> </td>
<td width="20" height="24"> </td>
<td width="50" height="24"> </td>
<td width="50" height="24"> </td>
<td width="50" height="24"> </td>
</tr>
<tr bgcolor="#000000">
<td width="50"> <input type="button" name="quad" value="^2" onclick="form.input.value = form.input.value * form.input.value" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #333333; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50"> <input type="button" name="root" value="root" onclick="Root()" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #333333; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50"> <input type="button" name="ln" value="ln" onclick="Ln()" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #333333; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="20"> </td>
<td width="50"> <input type="button" name="1/2" value="1/2" onclick="form.input.value += '0.5'" style="COLOR: #B3B300; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50"> <input type="button" name="1/3" value="1/3" onclick="form.input.value += '0.3333333333'" style="COLOR: #B3B300; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50"> <input type="button" name="1/4" value="1/4" onclick="form.input.value += '0.25'" style="COLOR: #B3B300; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
</tr>
<tr bgcolor="#000000">
<td width="50"> <input type="button" name="sin" value="sin" onclick="Sin()" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #333333; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50"> <input type="button" name="cos" value="cos" onclick="Cos()" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #333333; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50"> <input type="button" name="tan" value="tan" onclick="Tan()" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #333333; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="20"> </td>
<td width="50"> <input type="button" name="1/5" value="1/5" onclick="form.input.value += '0.2'" style="COLOR: #B3B300; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50"> <input type="button" name="1/6" value="1/6" onclick="form.input.value += '0.1666666667'" style="COLOR: #B3B300; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50"> <input type="button" name="1/7" value="1/7" onclick="form.input.value += '0.1428571429'" style="COLOR: #B3B300; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
</tr>
<tr bgcolor="#000000">
<td width="50"> <input type="button" name="sin2" value="asin" onclick="Isin()" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #333333; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50"> <input type="button" name="cos2" value="acos" onclick="Icos()" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #333333; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50"> <input type="button" name="tan2" value="atan" onclick="Itan()" style="COLOR: #FFFFFF; BACKGROUND-COLOR: #333333; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="20"> </td>
<td width="50"> <input type="button" name="1/8" value="1/8" onclick="form.input.value += '0.125'" style="COLOR: #B3B300; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50"> <input type="button" name="1/9" value="1/9" onclick="form.input.value += '0.1111111111'" style="COLOR: #B3B300; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
<td width="50"> <input type="button" name="1/10" value="1/10" onclick="form.input.value += '0.1'" style="COLOR: #B3B300; BACKGROUND-COLOR: #000000; HEIGHT: 25 px; WIDTH: 40px" /> </td>
</tr>
</tbody>
</table>
</form>
</div>
</body>
</html>
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