一个简单的jQuery计算器实现了连续计算功能

一个简单的jQuery计算器，只是实现了一个连续计算的功能

<!DOCTYPE html>
<html>
<head>
<meta charset="utf8"/>
<title>Javascript计算器</title>
</head>
<body>
<table>
<tr>
<td colspan="4"><input id="show" value="0"/></td>
</tr>
<tr>
<td><button onclick="number(this)" value="7">7</button></td>
<td><button onclick="number(this)" value="8">8</button></td>
<td><button onclick="number(this)" value="9">9</button></td>
<td><button onclick="calsym(this)" value="+">+</button></td>
</tr>
<tr>
<td><button onclick="number(this)" value="4">4</button></td>
<td><button onclick="number(this)" value="5">5</button></td>
<td><button onclick="number(this)" value="6">6</button></td>
<td><button onclick="calsym(this)" value="-">-</button></td>
</tr>
<tr>
<td><button onclick="number(this)" value="1">1</button></td>
<td><button onclick="number(this)" value="2">2</button></td>
<td><button onclick="number(this)" value="3">3</button></td>
<td><button onclick="calsym(this)" value="*">*</button></td>
</tr>
<tr>
<td><button onclick="number(this)" value="0">0</button></td>
<td><button onclick="calsym(this)" value="=">=</button></td>
<td><button onclick="clearCal()" value="c">c</button></td>
<td><button onclick="calsym(this)" value="/">/</button></td>
</tr>
</table>
</body>
<script type="text/javascript" src="jquery-1.9.1.js"></script>
<script type="text/javascript" src="jquery-1.9.1.min.js"></script>
<script type="text/javascript">
var num0 = null;
var num1 = null;
var symble = null;
var lastclick = null;
var symarr = new Array(); //符号集合
symarr[0] = '+';
symarr[1] = '/';
symarr[2] = '*';
symarr[3] = '-';
symarr[4] = '=';
function number(n){
var numnow = $('#show');
var _exist=$.inArray(lastclick,symarr); //判断上次点击是否为符号
if (numnow.val() == 0 || _exist != -1) {//若显示框为0 或者上次点击为符号，则重新记录显示框
numnow.val($(n).val());
}else{
numnow.val(parseInt(numnow.val()) * 10 +parseInt($(n).val()));
}
lastclick = $(n).val(); // 更新上次点击
} 

function calsym(cs){ //符号点击事件响应
var numnow = $('#show');
var _exist=$.inArray(lastclick,symarr);
if (num0 == null && symble == null) { //初始状态
num0 = numnow.val();
symble = $(cs).val();
}else if(num0 != null && num1 == null && _exist !=-1){ // 连续点操作符的处理，及第一次点击操作符处理
symble = $(cs).val();
}else{ //正常计算状态
num1 = numnow.val();
var result = calculate(symble,num0,num1);
symble = $(cs).val(); //上行及本行：先计算之前的运算符及结果，再更新运算符为本次点击
num0 = result;
numnow.val(result);
num1 = null;
}
lastclick = $(cs).val(); // 更新上次点击
} 

function clearCal(){ //清空函数
$('#show').val('0');
num0 = null;
num1 = null;
symble = null;
lastclick = null;
} 

function calculate(sym,m,n){ //计算并返回结果
var res = null;
m = parseInt(m);
n = parseInt(n);
switch(sym){
case '+':
res = m+n;
break;
case '-':
res = m-n;
break;
case '*':
res = m*n;
break;
case '/':
if (n == 0) {
alert("false");
break;
}
res = m/n;
break;
default:
break;
}
return res;
}
</script>
</html>