标签：
http://www.jb51.net/article/29295.htm
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>写给新手：js表单操作（四） 简单计算器（二）</title>
<style type="text/css">
body {
font-size: 12px;
font-family: Arial, Georgia, "Times New Roman", Times, serif;
color: #555;
text-align: center;
background-color: #e2e2e2;
}
h6 {
margin: 0;
font-size: 12px;
}
#calculator {
width: 240px;
height: auto;
overflow: hidden;
margin: 10px auto;
border: #fff 1px solid;
padding-bottom: 10px;
background-color: #f2f2f2;
}
#calculator div {
clear: both;
}
#calculator ul {
padding: 0;
margin: 5px 14px;
border: #fff 1px solid;
height: auto;
overflow: hidden
}
#calculator li {
list-style: none;
float: left;
width: 32px;
height: 32px;
margin: 5px;
display: inline;
line-height: 32px;
font-size: 14px;
background-color: #eaeaea;
}
#calculator li.tool {
background-color: #e2e2e2;
}
#calculator li:hover {
background-color: #f9f9f9;
cursor: pointer;
}
#calculator li:active {
background-color: #fc0;
cursor: pointer;
}
#calculator li.tool:active {
background-color: #d8e8ff;
cursor: pointer;
}
#calcu-head {
text-align: left;
padding: 10px 15px 5px;
}
span.imyeah {
float: right;
color: #ccc;
}
span.imyeah a {
color: #ccc;
}
.screen {
width: 200px;
height: 24px;
line-height: 24px;
padding: 4px;
border: #e6e6e6 1px solid;
border-bottom: #f2f2f2 1px solid;
border-right: #f2f2f2 1px solid;
margin: 10px auto;
direction: ltr;
text-align: right;
font-size: 16px;
color: #999;
}
#calcu-foot {
text-align: left;
padding: 10px 15px 5px;
height: auto;
overflow: hidden;
}
span#note {
float: left;
width: 210px;
height: auto;
overflow: hidden;
color: red;
}
span.welcome {
clear: both;
color: #999;
}
span.welcome a {
float: right;
color: #999;
}
</style>
<script language="javascript">
var num = 0,
result = 0,
numshow = "0";
var operate = 0; //判断输入状态的标志
var calcul = 0; //判断计算状态的标志
var quit = 0; //防止重复按键的标志
function command(num) {
var str = String(document.calculator.numScreen.value); //获得当前显示数据
str = (str != "0") ? ((operate == 0) ? str : "") : ""; //如果当前值不是"0"，且状态为0，则返回当前值，否则返回空值;
str = str + String(num); //给当前值追加字符
document.calculator.numScreen.value = str; //刷新显示
operate = 0; //重置输入状态
quit = 0; //重置防止重复按键的标志
}
function dzero() {
var str = String(document.calculator.numScreen.value);
str = (str != "0") ? ((operate == 0) ? str + "00" : "0") : "0"; //如果当前值不是"0"，且状态为0，则返回当str+"00"，否则返回"0";
document.calculator.numScreen.value = str;
operate = 0;
}
function dot() {
var str = String(document.calculator.numScreen.value);
str = (str != "0") ? ((operate == 0) ? str : "0") : "0"; //如果当前值不是"0"，且状态为0，则返回当前值，否则返回"0";
for (i = 0; i <= str.length; i++) { //判断是否已经有一个点号
if (str.substr(i, 1) == ".") return false; //如果有则不再插入
}
str = str + ".";
document.calculator.numScreen.value = str;
operate = 0;
}
function del() { //退格
var str = String(document.calculator.numScreen.value);
str = (str != "0") ? str : "";
str = str.substr(0, str.length - 1);
str = (str != "") ? str : "0";
document.calculator.numScreen.value = str;
}
function clearscreen() { //清除数据
num = 0;
result = 0;
numshow = "0";
document.calculator.numScreen.value = "0";
}
function plus() { //加法
calculate(); //调用计算函数
operate = 1; //更改输入状态
calcul = 1; //更改计算状态为加
}
function minus() { //减法
calculate();
operate = 1;
calcul = 2;
}
function times() { //乘法
calculate();
operate = 1;
calcul = 3;
}
function divide() { //除法
calculate();
operate = 1;
calcul = 4;
}
function persent() { //求余
calculate();
operate = 1;
calcul = 5;
}
function equal() {
calculate(); //等于
operate = 1;
num = 0;
result = 0;
numshow = "0";
}
//
function calculate() {
numshow = Number(document.calculator.numScreen.value);
if (num != 0 && quit != 1) { //判断前一个运算数是否为零以及防重复按键的状态
switch (calcul) { //判断要输入状态
case 1:
result = num + numshow;
break; //计算"+"
case 2:
result = num - numshow;
break; //计算"-"
case 3:
result = num * numshow;
break;
case 4:
if (numshow != 0) {
result = num / numshow;
} else {
document.getElementById("note").innerHTML = "被除数不能为零！";
setTimeout(clearnote, 4000)
}
break;
case 5:
result = num % numshow;
break;
}
quit = 1; //避免重复按键
} else {
result = numshow;
}
numshow = String(result);
document.calculator.numScreen.value = numshow;
num = result; //存储当前值
}
function clearnote() { //清空提示
document.getElementById("note").innerHTML = "";
}
</script>
</head>
<body>
<div id="calculator">
<div id="calcu-head"><span class="imyeah">? <a href="http://www.cnblogs.com/imyeah/" target="_blank">I‘m Yeah!</a></span>
<h6>简单的计算器</h6></div>
<form name="calculator" action="" method="get">
<div id="calcu-screen">
<!--配置显示窗口，使用onfocus="this.blur();"避免键盘输入-->
<input type="text" name="numScreen" class="screen" value="0" onfocus="this.blur();" />
</div>
<div id="calcu-btn">
<ul>
<!--配置按钮-->
<li onclick="command(7)">7</li>
<li onclick="command(8)">8</li>
<li onclick="command(9)">9</li>
<li class="tool" onclick="del()">←</li>
<li class="tool" onclick="clearscreen()">C</li>
<li onclick="command(4)">4</li>
<li onclick="command(5)">5</li>
<li onclick="command(6)">6</li>
<li class="tool" onclick="times()">×</li>
<li class="tool" onclick="divide()">÷</li>
<li onclick="command(1)">1</li>
<li onclick="command(2)">2</li>
<li onclick="command(3)">3</li>
<li class="tool" onclick="plus()">+</li>
<li class="tool" onclick="minus()">-</li>
<li onclick="command(0)">0</li>
<li onclick="dzero()">00</li>
<li onclick="dot()">.</li>
<li class="tool" onclick="persent()">%</li>
<li class="tool" onclick="equal()">=</li>
</ul>
</div>
<div id="calcu-foot">
<span id="note"></span>
<span class="welcome">欢迎使用javascript计算器！<a href="http://www.cnblogs.com/imyeah" target="_blank">反馈</a></span>
</div>
</form>
</div>
</body>
</html>
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原文地址：http://my.oschina.net/sfshine/blog/501868
