js制作简易计算器

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我是靠谱客的博主贪玩盼望，这篇文章主要介绍js制作简易计算器，现在分享给大家，希望可以做个参考。

制作能进行加减乘除的简易计算器，主要是练习动态注册事件。因以练习为主，所以包含了较多基础方法。

效果图

代码

复制代码

<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>简易计算器</title>
		<script type="text/javascript">
			window.onload = function(){
				document.onclick = function(){
					var ipts = document.getElementsByTagName("input");
					for (var i = 0; i < ipts.length; i++) {//得到值和符号
						if (ipts[i].type == "text") {
							switch (i){
								case 0:
									num1 = ipts[i].value;
									num1 = Number(num1);
									break;
								case 1:
									opt = ipts[i].value;
									break;
								case 2:
									num2 = ipts[i].value;
									num2 = Number(num2);
									break;
							}
						}
					}
					var res;//结果
					switch (opt){//通过得到的值和符号进行计算
						case "+":
							res = num1 + num2;
							break;
						case "-":
							res = num1 - num2;
							break;
						case "*":
							res = num1 * num2;
							break;
						case "/":
							res = num1 / num2;
							break;
					}
					
					var r = document.getElementById("result");
					r.value = res;
				}	
			}
		</script>
	</head>
	<body>
		<input type="text">
		<input type="text">
		<input type="text">=
		<input type="text" id="result">
		<input type="button" value="计算" id="btn">
	</body>
</html>

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<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>简易计算器</title>
		<script type="text/javascript">
			window.onload = function(){
				document.onclick = function(){
					var ipts = document.getElementsByTagName("input");
					for (var i = 0; i < ipts.length; i++) {//得到值和符号
						if (ipts[i].type == "text") {
							switch (i){
								case 0:
									num1 = ipts[i].value;
									num1 = Number(num1);
									break;
								case 1:
									opt = ipts[i].value;
									break;
								case 2:
									num2 = ipts[i].value;
									num2 = Number(num2);
									break;
							}
						}
					}
					var res;//结果
					switch (opt){//通过得到的值和符号进行计算
						case "+":
							res = num1 + num2;
							break;
						case "-":
							res = num1 - num2;
							break;
						case "*":
							res = num1 * num2;
							break;
						case "/":
							res = num1 / num2;
							break;
					}
					
					var r = document.getElementById("result");
					r.value = res;
				}	
			}
		</script>
	</head>
	<body>
		<input type="text">
		<input type="text">
		<input type="text">=
		<input type="text" id="result">
		<input type="button" value="计算" id="btn">
	</body>
</html>