多功能标准型计算器

实现一个标准型计算器及其各项功能的实现

效果图欣赏

在这里插入图片描述
是不是看起来很漂亮的呢？？？

功能详解：

屏幕显示输入的数字和符号
实现加减乘除运算
回退和清零功能
小数的运算
结果的输出

相信小伙伴们都已经迫不及待的想要知道源码了。

代码展示

HTML页面代码

<!DOCTYPE html>
<html><head><meta charset="utf-8"><title></title><link rel="stylesheet" href="css/com.css" type="text/css" /></head><body><table><tr><td colspan="4"><input class="screen" type="text" disabled /></td></tr><tr><td><input class="but_ac but" type="button" value="AC" style="color: orange"></td><td><input class="but_ac but" type="button" value="<—" style="color: orange"></td><td><input class="but" type="button" value="+/-"></td><td><input class="but" type="button" value="/"></td></tr><tr><td><input class="but" type="button" value="7"></td><td><input class="but" type="button" value="8"></td><td><input class="but" type="button" value="9"></td><td><input class="but" type="button" value="*"></td>  </tr><tr><td><input class="but" type="button" value="4"></td><td><input class="but" type="button" value="5"></td><td><input class="but" type="button" value="6"></td><td><input class="but" type="button" value="-"></td></tr><tr><td><input class="but" type="button" value="1"></td><td><input class="but" type="button" value="2"></td><td><input class="but" type="button" value="3"></td><td><input class="but" type="button" value="+"></td></tr><tr><td colspan="2"><input class="but" type="button" value="0" style="width: 180px"></td><td><input class="but" type="button" value="."></td><td><input class="but" type="button" value="=" style="background-color:orange ;color:white"></td></tr></table><script type="text/javascript" src="js/com.js"></script></body>
</html>

com.js代码

window.onload = function() {var num = document.getElementsByClassName("but"); var scr = document.getElementsByClassName("screen")[0]; for (var i = 0; i < num.length; i++) {num[i].onclick = function() {if (this.value == "AC") { scr.value = "";} else if (this.value == "+/-") { if (scr.value == "") {scr.value = "";}else if (isNaN(scr.value.charAt(scr.value.length - 1)) == false && isNaN(scr.value.charAt(scr.value.length - 2)) ==true) {scr.value = scr.value.substr(0, scr.value.length - 1) + "(" + "-" + scr.value.charAt(scr.value.length - 1) + ")";}}else if (this.value == "<—" && this.value != "") {scr.value = scr.value.substr(0, scr.value.length - 1);}else if (scr.value == "" && this.value == ".") {scr.value = "0.";}else if (this.value == "=") {scr.value = eval(scr.value);}else if (scr.value == "" && (this.value == "+" || this.value == "-" || this.value == "*" || this.value == "/")) {scr.value == "";} else {scr.value += this.value;}}}
}