js+html实现计算器

博客提到最后大概的效果,建议使用Chrome来实现。
<!Doctype html>
<html>
<head>
<meta charset="utf-8">
<style>
.main {
	width: 600px;
	height: 600px;
	border: 2px solid black;
	margin: 0 auto; 
	background: #F0FFFF;
	border-radius: 5px;
}
.screen {
	margin: 10px auto;
	width: 80%;
	height: 10%;
	border: 2px solid black;
	background: #E6E6FA;
	display: flex;
	border-radius: 5px;
	position: relative;
}
.operations{
	line-height:60px;
	font-size:20px;
}
.keyBoard {
	margin: 10px auto;
	width: 85%;
	height: 80%;
	border: 2px solid black;
	background: LightCyan;
	display: flex;
	flex-wrap: wrap;
	border-radius: 5px;
}
.keys {
	width: 120px;
	height: 20%;
	margin: 10px 1.5px;
	border: 2px solid black;
	font-family: fantasy;
	font-size: 20px;
	text-align: center;
	line-height: 100px;
	font-weight: bold;
	border-radius: 5px;
}
.keys:hover {
	background: #FFE4B5; 
}
#clear {
	margin-left: 420px;
	width: 58px;
	height: 58px;
	border: 2px solid black;
	border-radius: 29px;
	font-family: fantasy;
	font-size: 20px;
	text-align: center;
	font-weight: bold;
	position: fixed;
}
#clear:hover {
	background: #FFE4B5;
}
</style>
</head>
<body>
<div class="main">
	<div class="screen">
		<span class="operations" id="shu"></span>
		<span class="operations" id="operation"></span>
		<span class="operations" id="beiShu"></span>
		<div  class="operations" id="clear">清空</div>
	</div>
	<div class="keyBoard">
		<div class="keys" >7</div>
		<div class="keys" >8</div>
		<div class="keys" >9</div>
		<div class="keys" >*</div>
		<div class="keys" >4</div>
		<div class="keys" >5</div>
		<div class="keys" >6</div>
		<div class="keys" >-</div>
		<div class="keys" >1</div>
		<div class="keys" >2</div>
		<div class="keys" >3</div>
		<div class="keys" >+</div>
		<div class="keys" >0</div>
		<div class="keys" >.</div>
		<div class="keys" >=</div>
		<div class="keys" >/</div>
	</div>
</div>
<script src="https://cdn.bootcss.com/jquery/3.4.1/jquery.min.js"></script>
<script>
//加函数
var add = () => {
	let shuVal = $("#shu").html();
	let beiShuVal = $("#beiShu").html();
	let jianShu = Number(shuVal);
	let beiJianShu = Number(beiShuVal);
	if(shuVal == ""){
		alert("请输入加数");
	}
	if(beiShuVal == ""){
		alert("请输入被加数");
	}
	return jianShu+beiJianShu;
}
var sub = () => {
	let shuVal = $("#shu").html();
	let beiShuVal = $("#beiShu").html();
	let jianShu = Number(shuVal);
	let beiJianShu = Number(beiShuVal);
	if(shuVal == ""){
		alert("请输入被减数");
	}
	if(beiShuVal == ""){
		alert("请输入减数");
	}
	return jianShu-beiJianShu;
}
var mul = () => {
	let shuVal = $("#shu").html();
	let beiShuVal = $("#beiShu").html();
	let jianShu = Number(shuVal);
	let beiJianShu = Number(beiShuVal);
	if(shuVal == ""){
		alert("请输入被乘数");
	}
	if(beiShuVal == ""){
		alert("请输入乘数");
	}
	return jianShu*beiJianShu;
}
var chu = () => {
	let shuVal = $("#shu").html();
	let beiShuVal = $("#beiShu").html();
	let jianShu = Number(shuVal);
	let beiJianShu = Number(beiShuVal);
	if(shuVal == ""){
		alert("请输入被除数");
	}
	if(beiShuVal == ""){
		alert("请输入除数");
	}
	return jianShu/beiJianShu;
}

//获取按键DOM
var keys = document.getElementsByClassName("keys");

//加减乘除操作开关
var witch = false;
//0加1减2乘3除
var operation = 0;
//按键监听函数
var listenKeys = () => {
	for(let i=0; i < keys.length; i++){
		keys[i].onclick = function(){
			let type = this.innerText;
			let beiShu = $("#shu");
			let shu = $("#beiShu");
			let operationNode = $("#operation");
			console.log(type);
			switch (type) {
				case "1":
				{
					console.log("我到了");
					if(witch){
						shu.append(type);
					}else{
						beiShu.append(type);
					}
					break;
				}
				case "0":
				{
					if(witch){
						shu.append(type);
					}else{
						beiShu.append(type);
					}
					break;
				}
				case "2":
				{
					if(witch){
						shu.append(type);
					}else{
						beiShu.append(type);
					}
					break;
				}
				case "3":
				{
					if(witch){
						shu.append(type);
					}else{
						beiShu.append(type);
					}
					break;
				}
				case "4":
				{
					if(witch){
						shu.append(type);
					}else{
						beiShu.append(type);
					}
					break;
				}
				case "5":
				{
					if(witch){
						shu.append(type);
					}else{
						beiShu.append(type);
					}
					break;
				}
				case "6":
				{
					if(witch){
						shu.append(type);
					}else{
						beiShu.append(type);
					}
					break;
				}
				case "7":
				{
					if(witch){
						shu.append(type);
					}else{
						beiShu.append(type);
					}
					break;
				}
				case "8":
				{
					if(witch){
						shu.append(type);
					}else{
						beiShu.append(type);
					}
					break;
				}
				case "9":
				{
					if(witch){
						shu.append(type);
					}else{
						beiShu.append(type);
					}
					break;
				}
				case "+":
				{
					witch = true;
					operationNode.html(type);
					operation = 0;
					break;
				}
				case "-":
				{
					witch = true;
					operationNode.html(type);
					operation = 1;
					break;
				}
				case "*":
				{
					witch = true;
					operationNode.html(type);
					operation = 2;
					break;
				}
				case "/":
				{
					witch = true;
					operationNode.html(type);
					operation = 3;
					break;
				}
				case "=":
				{
					switch(operation){
						case 0:{
							let res = add();
							beiShu.html(res);
							shu.html("");
							operationNode.html("");
							witch = false;
							break;
						}
						case 1:{
							let res = sub();
							beiShu.html(res);
							shu.html("");
							operationNode.html("")
							witch = false;
							break;
						}
						case 2:{
							let res = mul();
							beiShu.html(res);
							shu.html("");
							operationNode.html("")
							witch = false;
							break;
						}
						case 3:{
							let res = chu();
							beiShu.html(res);
							shu.html("");
							operationNode.html("")
							witch = false;
							break;
						}
					}
					break;
				}
			}
		} 
	}
}


//清除函数
var clear = () => {
	$("#clear").click( () => {
		let beiShu = $("#shu");
		let shu = $("#beiShu");
		let operationNode = $("#operation");
		beiShu.html("");
		shu.html("");
		operationNode.html("");
	})
}

//主运行函数
var main = () => {
	listenKeys();
	clear();
}
main();
</script>
</body>
</html>

最后大概的效果是这样的,建议用chrome。

好的,以下是一个简单的HTML和JavaScript实现计算器的示例: ```html <!DOCTYPE html> <html> <head> <title>计算器</title> </head> <body> <input type="text" id="input" disabled><br> <button onclick="clearInput()">清空</button> <button onclick="backspace()">退格</button><br> <button onclick="appendToInput('7')">7</button> <button onclick="appendToInput('8')">8</button> <button onclick="appendToInput('9')">9</button> <button onclick="appendToInput('/')">÷</button><br> <button onclick="appendToInput('4')">4</button> <button onclick="appendToInput('5')">5</button> <button onclick="appendToInput('6')">6</button> <button onclick="appendToInput('*')">×</button><br> <button onclick="appendToInput('1')">1</button> <button onclick="appendToInput('2')">2</button> <button onclick="appendToInput('3')">3</button> <button onclick="appendToInput('-')">-</button><br> <button onclick="appendToInput('0')">0</button> <button onclick="appendToInput('.')">.</button> <button onclick="calculate()">=</button> <button onclick="appendToInput('+')">+</button><br> <script> function appendToInput(val) { document.getElementById('input').value += val; } function clearInput() { document.getElementById('input').value = ''; } function backspace() { var input = document.getElementById('input').value; document.getElementById('input').value = input.substring(0, input.length - 1); } function calculate() { var input = document.getElementById('input').value; var result = eval(input); document.getElementById('input').value = result; } </script> </body> </html> ``` 这个计算器的界面由一些按钮和一个输入框组成,按钮被点击时会调用对应的JavaScript函数。`appendToInput`函数用于将按钮的值添加到输入框中,`clearInput`函数用于清空输入框,`backspace`函数用于删除输入框中的最后一个字符,`calculate`函数用于计算输入框中的表达式并将结果显示在输入框中。注意,这个计算器的计算方法使用了JavaScript内置的`eval`函数,这个函数可以计算字符串表达式的值,但是需要注意安全问题。
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