先放图（好吧比较挫）
方法一：最容易版
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8" />
<title>简易计算器</title>
<style>
body {
background-color: #eee;
}
#calculator {
margin: 100px 0 0 150px;
}
</style>
</head>
<body> <!-- 简易计算器 -->
<div id="calculator">
<p>
<input type="text" class="formerInput" value="1" />
<span class="sign">+</span>
<input type="text" class="laterInput" value="1" />
<span>=</span>
<span class="resultOutput">2</span>
</p>
<p>
<input type="button" value="+" onclick="addHandler();" />
<input type="button" value="-" onclick="subtractHandler();" />
<input type="button" value="×" onclick="multiplyHandler();" />
<input type="button" value="÷" onclick="divideHandler();" />
</p>
</div> <script>
// 获取元素
var calculator = document.querySelector('#calculator');
var formerInput = calculator.querySelector('.formerInput');
var laterInput = calculator.querySelector('.laterInput');
var sign = calculator.querySelector('.sign');
var resultOutput = calculator.querySelector('.resultOutput'); // 加
function addHandler() {
sign.innerHTML = '+';
resultOutput.innerHTML = +formerInput.value + +laterInput.value;
}
// 减
function subtractHandler() {
sign.innerHTML = '-';
resultOutput.innerHTML = formerInput.value - laterInput.value;
}
// 乘
function multiplyHandler() {
sign.innerHTML = '×';
resultOutput.innerHTML = formerInput.value * laterInput.value;
}
// 除
function divideHandler() {
sign.innerHTML = '÷';
resultOutput.innerHTML = formerInput.value / laterInput.value;
}
</script>
</body>
</html>
方法二：结构和行为分离
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8" />
<title>简易计算器</title>
<style>
body {
background-color: #eee;
}
#calculator {
margin: 100px 0 0 150px;
}
</style>
</head>
<body> <!-- 简易计算器 -->
<div id="calculator">
<p>
<input type="text" class="formerInput" value="1" />
<span class="sign">+</span>
<input type="text" class="laterInput" value="1" />
<span>=</span>
<span class="resultOutput">2</span>
</p>
<p>
<input type="button" value="+" onclick="addHandler();" />
<input type="button" value="-" onclick="subtractHandler();" />
<input type="button" value="×" onclick="multiplyHandler();" />
<input type="button" value="÷" onclick="divideHandler();" />
</p>
</div> <script>
// 获取元素
var calculator = document.querySelector('#calculator');
var formerInput = calculator.querySelector('.formerInput');
var laterInput = calculator.querySelector('.laterInput');
var sign = calculator.querySelector('.sign');
var resultOutput = calculator.querySelector('.resultOutput');
var btns = calculator.querySelectorAll('.btn'); // 绑定事件
// +
btns[0].onclick = addHandler;
// -
btns[1].onclick = subtractHandler;
// ×
btns[2].onclick = multiplyHandler;
// ÷
btns[3].onclick = divideHandler; // 加
function addHandler() {
sign.innerHTML = '+';
resultOutput.innerHTML = +formerInput.value + +laterInput.value;
}
// 减
function subtractHandler() {
sign.innerHTML = '-';
resultOutput.innerHTML = formerInput.value - laterInput.value;
}
// 乘
function multiplyHandler() {
sign.innerHTML = '×';
resultOutput.innerHTML = formerInput.value * laterInput.value;
}
// 除
function divideHandler() {
sign.innerHTML = '÷';
resultOutput.innerHTML = formerInput.value / laterInput.value;
}
</script>
</body>
</html>
方法三：循环绑定事件
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8" />
<title>简易计算器</title>
<style>
body {
background-color: #eee;
}
#calculator {
margin: 100px 0 0 150px;
}
</style>
</head>
<body> <!-- 简易计算器 -->
<div id="calculator">
<p>
<input type="text" class="formerInput" value="1" />
<span class="sign">+</span>
<input type="text" class="laterInput" value="1" />
<span>=</span>
<span class="resultOutput">2</span>
</p>
<p>
<input type="button" value="+" onclick="addHandler();" />
<input type="button" value="-" onclick="subtractHandler();" />
<input type="button" value="×" onclick="multiplyHandler();" />
<input type="button" value="÷" onclick="divideHandler();" />
</p>
</div> <script>
// 获取元素
var calculator = document.querySelector('#calculator');
var formerInput = calculator.querySelector('.formerInput');
var laterInput = calculator.querySelector('.laterInput');
var sign = calculator.querySelector('.sign');
var resultOutput = calculator.querySelector('.resultOutput');
var btns = calculator.querySelectorAll('.btn'); // 绑定事件
for (var i = 0; i < btns.length; i++) {
btns[i].onclick = function () {
switch (this.title) {
case 'add':
addHandler();
break;
case 'subtract':
subtractHandler();
break;
case 'multiply':
multiplyHandler();
break;
case 'divide':
divideHandler();
break;
}
};
} // 加
function addHandler() {
sign.innerHTML = '+';
resultOutput.innerHTML = +formerInput.value + +laterInput.value;
}
// 减
function subtractHandler() {
sign.innerHTML = '-';
resultOutput.innerHTML = formerInput.value - laterInput.value;
}
// 乘
function multiplyHandler() {
sign.innerHTML = '×';
resultOutput.innerHTML = formerInput.value * laterInput.value;
}
// 除
function divideHandler() {
sign.innerHTML = '÷';
resultOutput.innerHTML = formerInput.value / laterInput.value;
}
</script>
</body>
</html>
方法四：提取函数
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8" />
<title>简易计算器</title>
<style>
body {
background-color: #eee;
}
#calculator {
margin: 100px 0 0 150px;
}
</style>
</head>
<body> <!-- 简易计算器 -->
<div id="calculator">
<p>
<input type="text" class="formerInput" value="1" />
<span class="sign">+</span>
<input type="text" class="laterInput" value="1" />
<span>=</span>
<span class="resultOutput">2</span>
</p>
<p>
<input type="button" value="+" class="btn" title="add" />
<input type="button" value="-" class="btn" title="subtract" />
<input type="button" value="×" class="btn" title="multiply" />
<input type="button" value="÷" class="btn" title="divide" />
</p>
</div> <script>
// 获取元素
var calculator = document.querySelector('#calculator');
var formerInput = calculator.querySelector('.formerInput');
var laterInput = calculator.querySelector('.laterInput');
var sign = calculator.querySelector('.sign');
var resultOutput = calculator.querySelector('.resultOutput');
var btns = calculator.querySelectorAll('.btn'); // 绑定事件
each(btns, function (index, elem ) {
elem.onclick = function () {
switch (this.title) {
case 'add':
addHandler();
break;
case 'subtract':
subtractHandler();
break;
case 'multiply':
multiplyHandler();
break;
case 'divide':
divideHandler();
break;
}
};
}); // 遍历
function each(array, fn) {
for (var i = 0; i < array.length; i++) {
fn(i, array[i]);
}
} // 更新符号
function updateSign(symbol) {
sign.innerHTML = symbol;
} // 加法
function add(num1, num2) {
return +num1 + +num2;
}
// 减法
function subtract(num1, num2) {
return num1 - num2;
}
// 乘法
function multiply(num1, num2) {
return num1 * num2;
}
// 除法
function divide(num1, num2) {
return num1 / num2;
} // 输出结果
function outputResult(result) {
resultOutput.innerHTML = result;
} // 加
function addHandler() {
// sign.innerHTML = '+';
updateSign('+');
outputResult(add(formerInput.value, laterInput.value));
}
// 减
function subtractHandler() {
updateSign('-');
outputResult(subtract(formerInput.value, laterInput.value));
}
// 乘
function multiplyHandler() {
updateSign('×');
outputResult(multiply(formerInput.value, laterInput.value));
}
// 除
function divideHandler() {
updateSign('÷');
outputResult(divide(formerInput.value, laterInput.value));
}
</script>
</body>
</html>
方法五：管理代码(找到组织)
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8" />
<title>简易计算器</title>
<style>
body {
background-color: #eee;
}
#calculator {
margin: 100px 0 0 150px;
}
</style>
</head>
<body> <!-- 简易计算器 -->
<div id="calculator">
<p>
<input type="text" class="formerInput" value="1" />
<span class="sign">+</span>
<input type="text" class="laterInput" value="1" />
<span>=</span>
<span class="resultOutput">2</span>
</p>
<p>
<input type="button" value="+" class="btn" title="add" />
<input type="button" value="-" class="btn" title="subtract" />
<input type="button" value="×" class="btn" title="multiply" />
<input type="button" value="÷" class="btn" title="divide" />
</p>
</div> <script>
// 获取元素
var wrapElem = document.querySelector('#calculator');
var calculatorElem = {
formerInput: wrapElem.querySelector('.formerInput'),
laterInput: wrapElem.querySelector('.laterInput'),
sign: wrapElem.querySelector('.sign'),
resultOutput: wrapElem.querySelector('.resultOutput'),
btns: wrapElem.querySelectorAll('.btn')
}; // 绑定事件
each(calculatorElem.btns, function (index, elem ) {
elem.onclick = function () {
switch (this.title) {
case 'add':
addHandler();
break;
case 'subtract':
subtractHandler();
break;
case 'multiply':
multiplyHandler();
break;
case 'divide':
divideHandler();
break;
}
};
}); // 遍历
function each(array, fn) {
for (var i = 0; i < array.length; i++) {
fn(i, array[i]);
}
} // 更新符号
function updateSign(symbol) {
calculatorElem.sign.innerHTML = symbol;
} var operation = {
add: function(num1, num2) {
return +num1 + +num2;
},
subtract: function(num1, num2) {
return num1 - num2;
},
multiply: function(num1, num2) {
return num1 * num2;
},
divide: function(num1, num2) {
return num1 / num2;
}
}; // 输出结果
function outputResult(result) {
calculatorElem.resultOutput.innerHTML = result;
} // 加
function addHandler() {
// sign.innerHTML = '+';
updateSign('+');
outputResult(operation.add(calculatorElem.formerInput.value, calculatorElem.laterInput.value));
}
// 减
function subtractHandler() {
updateSign('-');
outputResult(operation.subtract(calculatorElem.formerInput.value, calculatorElem.laterInput.value));
}
// 乘
function multiplyHandler() {
updateSign('×');
outputResult(operation.multiply(calculatorElem.formerInput.value, calculatorElem.laterInput.value));
}
// 除
function divideHandler() {
updateSign('÷');
outputResult(operation.divide(calculatorElem.formerInput.value, calculatorElem.laterInput.value));
}
</script>
</body>
</html>
方法六：OCP开放--封闭原则
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8" />
<title>简易计算器</title>
<style>
body {
background-color: #eee;
}
#calculator {
margin: 100px 0 0 150px;
}
</style>
</head>
<body> <!-- 简易计算器 -->
<div id="calculator">
<p>
<input type="text" class="formerInput" value="1" />
<span class="sign">+</span>
<input type="text" class="laterInput" value="1" />
<span>=</span>
<span class="resultOutput">2</span>
</p>
<p>
<input type="button" value="+" class="btn" title="add" />
<input type="button" value="-" class="btn" title="subtract" />
<input type="button" value="×" class="btn" title="multiply" />
<input type="button" value="÷" class="btn" title="divide" />
<input type="button" value="%" class="btn" title="mod" />
<input type="button" value="^" class="btn" title="power" />
<!-- <input type="button" value="1/x" class="btn" title="invert" /> -->
</p>
</div> <script>
// 获取元素
var wrapElem = document.querySelector('#calculator');
var calculatorElem = {
formerInput: wrapElem.querySelector('.formerInput'),
laterInput: wrapElem.querySelector('.laterInput'),
sign: wrapElem.querySelector('.sign'),
resultOutput: wrapElem.querySelector('.resultOutput'),
btns: wrapElem.querySelectorAll('.btn')
}; // 绑定事件
each(calculatorElem.btns, function (index, elem ) {
elem.onclick = function () {
updateSign(this.value);
outputResult(operate(this.title, calculatorElem.formerInput.value, calculatorElem.laterInput.value));
};
}); // 遍历
function each(array, fn) {
for (var i = 0; i < array.length; i++) {
fn(i, array[i]);
}
} // 更新符号
function updateSign(symbol) {
calculatorElem.sign.innerHTML = symbol;
} // 运算
function operate(name, num1, num2) {
if (!operation[name]) throw new Error('不存在名为' + name + '的运算方法！');
return operation[name](num1, num2);
} var operation = {
add: function(num1, num2) {
return +num1 + +num2;
},
subtract: function(num1, num2) {
return num1 - num2;
},
multiply: function(num1, num2) {
return num1 * num2;
},
divide: function(num1, num2) {
return num1 / num2;
},
addOperation: function (name, fn) {
if (!this[name]) {
this[name] = fn;
}
return this;
}
}; operation.addOperation('mod', function (num1, num2) {
return num1 % num2;
}).addOperation('power', function (base, power) {
return Math.pow(base, power);
}); // 输出结果
function outputResult(result) {
calculatorElem.resultOutput.innerHTML = result;
}
</script>
</body>
</html>
方法七：模块化
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8" />
<title>简易计算器</title>
<style>
body {
background-color: #eee;
}
#calculator {
margin: 100px 0 0 150px;
}
</style>
</head>
<body> <!-- 简易计算器 -->
<div id="calculator">
<p>
<input type="text" class="formerInput" value="1" />
<span class="sign">+</span>
<input type="text" class="laterInput" value="1" />
<span>=</span>
<span class="resultOutput">2</span>
</p>
<p>
<input type="button" value="+" class="btn" title="add" />
<input type="button" value="-" class="btn" title="subtract" />
<input type="button" value="×" class="btn" title="multiply" />
<input type="button" value="÷" class="btn" title="divide" />
<input type="button" value="%" class="btn" title="mod" />
<input type="button" value="^" class="btn" title="power" />
<input type="button" value="1/x" class="btn" title="invert" />
</p>
</div> <script> (function () {
// 获取元素
var wrapElem = document.querySelector('#calculator');
var calculatorElem = {
formerInput: wrapElem.querySelector('.formerInput'),
laterInput: wrapElem.querySelector('.laterInput'),
sign: wrapElem.querySelector('.sign'),
resultOutput: wrapElem.querySelector('.resultOutput'),
btns: wrapElem.querySelectorAll('.btn')
}; // 绑定事件
each(calculatorElem.btns, function (index, elem ) {
elem.onclick = function () {
updateSign(this.value);
outputResult(operate(this.title, calculatorElem.formerInput.value, calculatorElem.laterInput.value));
};
}); // 遍历
function each(array, fn) {
for (var i = 0; i < array.length; i++) {
fn(i, array[i]);
}
} // 更新符号
function updateSign(symbol) {
calculatorElem.sign.innerHTML = symbol;
} // 运算
var operate = (function () {
var operation = {
add: function(num1, num2) {
return +num1 + +num2;
},
subtract: function(num1, num2) {
return num1 - num2;
},
multiply: function(num1, num2) {
return num1 * num2;
},
divide: function(num1, num2) {
return num1 / num2;
},
addOperation: function (name, fn) {
if (!operation[name]) {
operation[name] = fn;
}
return operation;
}
}; function operate(name) {
if (!operation[name]) throw new Error('不存在名为' + name + '的运算方法！');
return operation[name].apply(operation, [].slice.call(arguments, 1, arguments.length));
}
operate.addOperation = operation.addOperation; return operate;
})(); operate.addOperation('mod', function (num1, num2) {
return num1 % num2;
}).addOperation('power', function (base, power) {
return Math.pow(base, power);
}).addOperation('invert', function (num) {
return 1 / num;
}); // 输出结果
function outputResult(result) {
calculatorElem.resultOutput.innerHTML = result;
}
})(); </script>
</body>
</html>