Javascript计算器 
 
 
 
 
 
 
 
7 
8 
9 
+ 
 
 
4 
5 
6 
- 
 
 
1 
2 
3 
* 
 
 
0 
= 
c 
/ 
 
 
 
 
 
 
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; 
}