HTML+CSS+JS实现计算器

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课程名：HTML+CSS+JS

内容/作用：知识点/设计/实验/作业/练习

学习：HTML+CSS+JS

思路

创建HTML页面，包含数字和操作符的按钮以及一个输出框
使用CSS样式美化页面
使用JavaScript编写计算器的逻辑，通过绑定事件处理程序，实现对按钮的响应和输出结果到输出框

效果图

在这里插入图片描述

代码

HTML:

<!DOCTYPE html>
<html>
<head><meta charset="UTF-8"><title>Calculator</title><link rel="stylesheet" href="style.css">
</head>
<body><div class="calculator"><div class="output"><input type="text" id="result" disabled></div><div class="btn-row"><button class="operator" id="clear">C</button><button class="operator" id="backspace">CE</button><button class="operator" id="divide">/</button><button class="operator" id="multiply">*</button></div><div class="btn-row"><button class="number" id="7">7</button><button class="number" id="8">8</button><button class="number" id="9">9</button><button class="operator" id="minus">-</button></div><div class="btn-row"><button class="number" id="4">4</button><button class="number" id="5">5</button><button class="number" id="6">6</button><button class="operator" id="plus">+</button></div><div class="btn-row"><button class="number" id="1">1</button><button class="number" id="2">2</button><button class="number" id="3">3</button><button class="operator" id="equals">=</button></div><div class="btn-row"><button class="number" id="0">0</button><button class="operator" id="decimal">.</button></div></div><script src="app.js"></script>
</body>
</html>

CSS:

* {margin: 0;padding: 0;box-sizing: border-box;font-family: Arial, sans-serif;
}.calculator {margin: 50px auto;width: 300px;background-color: #eee;border-radius: 10px;padding: 20px;box-shadow: 0 0 15px rgba(0, 0, 0, 0.2);
}.output {margin-bottom: 20px;
}#result {width: 100%;font-size: 2em;text-align: right;padding: 5px;background-color: #fff;border: none;border-radius: 5px;box-shadow: inset 0 0 5px rgba(0, 0, 0, 0.1);
}.btn-row {display: flex;justify-content: space-between;margin-bottom: 5px;
}button {background-color: #fff;color: #333;font-size: 1.5em;border: none;border-radius: 5px;padding: 10px;width: 70px;height: 70px;box-shadow: 0 0 5px rgba(0, 0, 0, 0.1);cursor: pointer;transition: all 0.3s ease;
}button:hover {background-color: #333;color: #fff;box-shadow: 0 0 10px rgba(0, 0, 0, 0.2);
}.number {background-color: #eee;
}.operator {background-color: #f2a53f;color: #fff;
}.btn-row:last-child button {width: 150px;
}.btn-row:last-child button#decimal {width: 70px;
}.btn-row:last-child button#0 {width: 150px;
}

JavaScript:

//获取DOM元素
const result = document.getElementById("result");
const clearBtn = document.getElementById("clear");
const backspaceBtn = document.getElementById("backspace");
const divideBtn = document.getElementById("divide");
const multiplyBtn = document.getElementById("multiply");
const minusBtn = document.getElementById("minus");
const plusBtn = document.getElementById("plus");
const equalsBtn = document.getElementById("equals");
const decimalBtn = document.getElementById("decimal");
const numberBtns = document.querySelectorAll(".number");let currentOperation = null;
let firstOperand = null;//添加事件监听器
clearBtn.addEventListener("click", () => {resetCalculator();
});backspaceBtn.addEventListener("click", () => {result.value = result.value.slice(0, -1);
});divideBtn.addEventListener("click", () => {setOperation("/");
});multiplyBtn.addEventListener("click", () => {setOperation("*");
});minusBtn.addEventListener("click", () => {setOperation("-");
});plusBtn.addEventListener("click", () => {setOperation("+");
});equalsBtn.addEventListener("click", () => {if (currentOperation !== null) {compute();currentOperation = null;}
});decimalBtn.addEventListener("click", () => {if (!result.value.includes(".")) {result.value += ".";}
});numberBtns.forEach((button) => {button.addEventListener("click", () => {if (result.value === "0") {result.value = button.innerText;} else {result.value += button.innerText;}});
});//重置计算器
function resetCalculator() {currentOperation = null;firstOperand = null;result.value = "0";
}//设置操作符
function setOperation(operator) {if (currentOperation !== null) {compute();}currentOperation = operator;firstOperand = parseFloat(result.value);result.value = "0";
}//计算结果
function compute() {const secondOperand = parseFloat(result.value);let resultValue;switch (currentOperation) {case "+":resultValue = firstOperand + secondOperand;break;case "-":resultValue = firstOperand - secondOperand;break;case "*":resultValue = firstOperand * secondOperand;break;case "/":resultValue = firstOperand / secondOperand;break;default:return;}result.value = resultValue;firstOperand = resultValue;
}