图片：
实现代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
<style>
body {
padding: 20px;
font-family: Arial;
}
.calc-wrap {
width: 300px;
border: 1px solid #ddd;
border-radius: 3px;
}
.calc-operation {
width: 100%;
border-collapse: collapse;
}
.calc-in-out {
width: 100%;
padding: 10px 20px;
text-align: right;
box-sizing: border-box;
background-color: rgba(250, 250, 250, .9);
}
.calc-in-out p {
overflow: hidden;
margin: 5px;
width: 100%;
}
.calc-history {
margin-left: -20px;
font-size: 18px;
color: #bbb;
border-bottom: 1px dotted #ddf;
min-height: 23px;
}
.calc-in,
.calc-out {
font-size: 20px;
color: #888;
line-height: 39px;
min-height: 39px;
}
.calc-in {
color: #888;
}
.calc-out {
color: #ccc;
}
.calc-in.active,
.calc-out.active {
font-size: 34px;
color: #666;
}
.calc-operation td {
padding: 10px;
width: 25%;
text-align: center;
border: 1px solid #ddd;
font-size: 26px;
color: #888;
cursor: pointer;
}
.calc-operation td:active {
background-color: #ddd;
}
.calc-operation .cls {
color: #ee8956;
}
</style>
<script src="../plug/jquery-3.2.0.min.js"></script>
</head>
<body>
<h5>计算计算</h5>
<!-- 计算器 -->
<div class="calc-wrap">
<div class="calc-in-out">
<!-- 上一条运算记录 -->
<p class="calc-history" title=""></p>
<!-- 输入的数据 -->
<p class="calc-in"></p>
<!-- 输出的运算结果 -->
<p class="calc-out active"></p>
</div>
<table class="calc-operation">
<thead></thead>
<tbody>
<tr>
<td data-ac="cls" class="cls">C</td>
<td data-ac="del">←</td>
<td data-ac="sq">x<sup>2</sup></td>
<td data-ac="mul">×</td>
</tr>
<tr>
<td data-val="7">7</td>
<td data-val="8">8</td>
<td data-val="9">9</td>
<td data-ac="div">÷</td>
</tr>
<tr>
<td data-val="4">4</td>
<td data-val="5">5</td>
<td data-val="6">6</td>
<td data-ac="plus">+</td>
</tr>
<tr>
<td data-val="1">1</td>
<td data-val="2">2</td>
<td data-val="3">3</td>
<td data-ac="minus">-</td>
</tr>
<td data-ac="per">%</td>
<td data-val="0">0</td>
<td data-ac="dot">.</td>
<td data-ac="eq" class="eq">=</td>
</tbody>
</table>
</div>
</body>
<script>
$(function() {
function Calculator($dom) {
this.$dom = $($dom);
// 历史运算
this.$history = this.$dom.find('.calc-history');
// 输入区
this.$in = this.$dom.find('.calc-in');
// 输出区
this.$out = this.$dom.find('.calc-out');
this.$operation = this.$dom.find('.calc-operation');
// 运算符映射
this.op = {
'plus': '+',
'minus': '-',
'mul': '*',
'div': '/'
};
this.opArr = ['+', '-', '*', '/'];
// 中缀表达式
this.infix = [];
// 后缀表达式
this.suffix = [];
// 后缀表达式运算结果集
this.result = [];
// 存储最近的值
this.lastVal = 0;
// 当前已经计算等于完成
this.calcDone = false;
// 当前正在进行小数点点（.）相关值的修正
this.curDot = false;
this.init();
}
Calculator.prototype = {
constructor: Calculator,
// 初始化
init: function() {
this.bindEvent();
},
// 绑定事件
bindEvent: function() {
var that = this;
that.$operation.on('click', function(e) {
e = e || window.event;
var elem = e.target || e.srcElement,
val,
action;
if (elem.tagName === 'TD') {
val = elem.getAttribute('data-val') || elem.getAttribute('data-ac');
// 数字：0-9
if (!isNaN(parseInt(val, 10))) {
// 构建中缀表达式并显示
var infixRe = that.buildInfix(parseInt(val, 10), 'add');
that.$in.text(infixRe.join('')).addClass('active');
that.calculate();
return;
}
action = val;
// 操作：清除、删除、计算等于
if (['cls', 'del', 'eq'].indexOf(action) !== -1) {
if (!that.infix.length) {
return;
}
// 清空数据
if (action === 'cls' || (action === 'del' && that.calcDone)) {
that.$in.text('');
that.$out.text('');
that.resetData();
}
// 清除
else if (action === 'del') {
// 重新构建中缀表达式
var infixRe = that.buildInfix(that.op[action], 'del');
that.$in.text(infixRe.join('')).addClass('active');
that.calculate();
}
// 等于
else if (action === 'eq') {
that.calculate('eq');
}
}
// 预运算：百分比、小数点、平方
else if (['per', 'dot', 'sq'].indexOf(action) !== -1) {
if (!that.infix.length || that.isOp(that.lastVal)) {
return;
}
if (action === 'per') {
that.lastVal /= 100;
} else if (action === 'sq') {
that.lastVal *= that.lastVal;
} else if (action === 'dot') {
// that.curDot = true;
}
// 重新构建中缀表达式
var infixRe = that.buildInfix(that.lastVal, 'change');
that.$in.text(infixRe.join('')).addClass('active');
that.calculate();
}
// 运算符：+ - * /
else if (that.isOp(that.op[action])) {
if (!that.infix.length && (that.op[action] === '*' || that.op[action] === '/')) {
return;
}
var infixRe = that.buildInfix(that.op[action], 'add');
that.$in.text(infixRe.join('')).addClass('active');
}
}
});
},
resetData: function() {
this.infix = [];
this.suffix = [];
this.result = [];
this.lastVal = 0;
this.curDot = false;
},
// 构建中缀表达式
buildInfix: function(val, type) {
// 直接的点击等于运算之后，
if (this.calcDone) {
this.calcDone = false;
// 再点击数字，则进行新的运算
if (!this.isOp(val)) {
this.resetData();
}
// 再点击运算符，则使用当前的结果值继续进行运算
else {
var re = this.result[0];
this.resetData();
this.infix.push(re);
}
}
var newVal;
// 删除操作
if (type === 'del') {
newVal = this.infix.pop();
// 删除末尾一位数
newVal = Math.floor(newVal / 10);
if (newVal) {
this.infix.push(newVal);
}
this.lastVal = this.infix[this.infix.length - 1];
return this.infix;
}
// 添加操作，首先得判断运算符是否重复
else if (type === 'add') {
// 两个连续的运算符
if (this.isOp(val) && this.isOp(this.lastVal)) {
return this.infix;
}
// 两个连续的数字
else if (!this.isOp(val) && !this.isOp(this.lastVal)) {
newVal = this.lastVal * 10 + val;
this.infix.pop();
this.infix.push(this.lastVal = newVal);
return this.infix;
}
// 首个数字正负数
if (!this.isOp(val) && this.infix.length === 1 && (this.lastVal === '+' || this.lastVal === '-')) {
newVal = this.lastVal === '+' ? val : 0 - val;
this.infix.pop();
this.infix.push(this.lastVal = newVal);
return this.infix;
}
// TODO: 小数点运算
// if (this.isOp(val)) {
// this.curDot = false;
// }
// // 小数点
// if (this.curDot) {
// var dotLen = 0;
// newVal = this.infix.pop();
// dotLen = newVal.toString().split('.');
// dotLen = dotLen[1] ? dotLen[1].length : 0;
// newVal += val / Math.pow(10, dotLen + 1);
// // 修正小数点运算精确值
// newVal = parseFloat(newVal.toFixed(dotLen + 1));
// this.infix.push(this.lastVal = newVal);
// return this.infix;
// }
this.infix.push(this.lastVal = val);
return this.infix;
}
// 更改操作，比如%的预运算
else if (type === 'change') {
this.infix.pop();
this.infix.push(this.lastVal = val);
return this.infix;
}
},
// 判断是否为运算符
isOp: function(op) {
return op && this.opArr.indexOf(op) !== -1;
},
// 判断运算符优先级
priorHigher: function(a, b) {
return (a === '+' || a === '-') && (b === '*' || b === '/');
},
// 进行运算符的运算
opCalc: function(b, op, a) {
return op === '+'
? a + b
: op === '-'
? a - b
: op === '*'
? a * b
: op === '/'
? a / b
: 0;
},
// 即时得进行运算
calculate: function(type) {
this.infix2Suffix();
var suffixRe = this.calcSuffix();
if (suffixRe) {
this.$out.text('=' + suffixRe)
.attr('title', suffixRe)
.removeClass('active');
// 如果是直接显示地进行等于运算
if (type === 'eq') {
this.$in.removeClass('active');
this.$out.addClass('active');
// 设置标记：当前已经显示地进行计算
this.calcDone = true;
this.lastVal = suffixRe;
// 设置历史记录
var history = this.infix.join('') + ' = ' + suffixRe;
this.$history.text(history).attr('title', history);
}
}
},
// 中缀表达式转后缀
infix2Suffix: function() {
var temp = [];
this.suffix = [];
for (var i = 0; i < this.infix.length; i++) {
// 数值，直接压入
if (!this.isOp(this.infix[i])) {
this.suffix.push(this.infix[i]);
}
else {
if (!temp.length) {
temp.push(this.infix[i]);
}
else {
var opTop = temp[temp.length - 1];
// 循环判断运算符优先级，将运算符较高的压入后缀表达式
if (!this.priorHigher(opTop, this.infix[i])) {
while (temp.length && !this.priorHigher(opTop, this.infix[i])) {
this.suffix.push(temp.pop());
opTop = temp[temp.length - 1];
}
}
// 将当前运算符也压入后缀表达式
temp.push(this.infix[i]);
}
}
}
// 将剩余运算符号压入
while (temp.length) {
this.suffix.push(temp.pop());
}
},
// 后缀表达式计算
calcSuffix: function() {
this.result = [];
for (var i = 0; i < this.suffix.length; i++) {
// 数值，直接压入结果集
if (!this.isOp(this.suffix[i])) {
this.result.push(this.suffix[i]);
}
// 运算符，从结果集中取出两项进行运算，并将运算结果置入结果集合
else {
this.result.push(this.opCalc(this.result.pop(), this.suffix[i], this.result.pop()));
}
}
// 此时结果集中只有一个值，即为结果
return this.result[0];
}
};
new Calculator('.calc-wrap');
});
</script>
</html>
