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简单计算器实现

2017-07-26 20:39 169 查看
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>04-00-计算器</title>
<style>
*{margin: 0;padding: 0;left: 0; top: 0; list-style: none;}
ul{
margin: 50px;
margin-top: 20px;
width: 280px;
}

ul li{
float: left;
width: 45px;
height: 45px;
border: 1px solid #aaa;
margin: 10px;
text-align: center;
line-height: 45px;
font-family: 微软雅黑;
font-size: 16px;
font-weight: bolder;
cursor: pointer;
}

ul li:nth-child(3), ul li:nth-last-child(3){
width: 110px;
}

.r{
width: 244px;
height: 80px;
border: 1px solid #aaa;
margin-top: 50px;
margin-left: 60px;
font-family: 微软雅黑;
font-size: 20px;
text-align: right;
line-height: 80px;
overflow: hidden;
/*overflow-x: scroll;*/
}
</style>
<!-- <link rel="stylesheet" href="./css/cal.css">
<script src="./js/cal.js"></script> -->
<!-- <script src='../day1/js/my.js'></script> -->
</head>
<body>
<div class="r"></div>
<ul>
<li>退格</li>
<li>C</li>
<li>=</li>
<li>1</li>
<li>2</li>
<li>3</li>
<li>+</li>
<li>4</li>
<li>5</li>
<li>6</li>
<li>-</li>
<li>7</li>
<li>8</li>
<li>9</li>
<li>*</li>
<li>0</li>
<li>.</li>
<li>/</li>
</ul>
<script>
var lis     = document.querySelectorAll('ul li');
var r       = document.querySelector('.r');
for (var i = 0; i < lis.length; i++) {
lis[i].onclick = function () {
/* body... */
var ih = this.innerHTML;
var rh = r.innerHTML;
var oper = ['+', '-', '*', '/'];
switch (ih) {
case '退格':
// statements_1
rh = rh.slice(0, -1);
console.log(rh);
r.innerHTML = rh;
break;

case 'C':
r.innerHTML = '';
break;

case '=':
var result  = eval(r.innerHTML); //eval:执行jS代码
var haha=result-parseInt(result);
console.log(haha);
if(haha>0){
r.innerHTML = result.toFixed(2);
// 保留两位小数并四舍五入

}else{
console.log(result);

r.innerHTML=result;
}
//保留两位小数

break;

case '*':
case '/':
var lc = rh.slice(-1);
if(rh == ''||oper.indexOf(lc) > -1){
return ;
}else{
r.innerHTML += ih;
}

// console.log(oper.indexOf(lc));

break;
case '.':

var zz=/[+*/-]/ig;
var arrnumber=rh.split(zz);
var zzz=/\./ig;

console.log(arrnumber);

var lc = rh.slice(-1);

// var narr = rh.split(); //用正则分割成数组
if(!rh || isNaN(lc)||zzz.test(arrnumber[arrnumber.length-1])){
return ;
}else{
r.innerHTML += ih;
}

break;
case '+':
case '-':

var lc = rh.slice(-1);
// console.log(oper.indexOf(lc));
if(oper.indexOf(lc) > -1){
return ;
}
else{
r.innerHTML += ih;

}
break;
default:
r.innerHTML += ih;

}
}
}

</script>
</body>
</html>
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标签： 计算器
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