HTML 和 JS
<!DOCTYPE html>
<html>
<head>
<title>Calculator</title>
<!-- Allows me to use jQuery -->
<script>
if (typeof module === 'object') {window.module = module; module = undefined;}
</script>
<script src="assets/libraries/jq.js"></script>
<link rel="stylesheet" href="assets/css/style.css">
<!-- End of "Allows me to use jQuery" -->
<script>
if (window.module) module = window.module;
</script>
</head>
<body>
<!-- "vysledek" means in English "result" -->
<input id="vysledek" type="text" autofocus>
<br>
<!-- "kalkulacka" means in my language "calculator" -->
<button class="C" onClick="kalkulacka('C')">C</button>
<button onClick="kalkulacka('(')">(</button>
<button onClick="kalkulacka(')')">)</button>
<button onClick="kalkulacka('/')">÷</button>
<br>
<button onClick="kalkulacka(7)">7</button>
<button onClick="kalkulacka(8)">8</button>
<button onClick="kalkulacka(9)">9</button>
<button onClick="kalkulacka('*')">×</button>
<br>
<button onClick="kalkulacka(4)">4</button>
<button onClick="kalkulacka(5)">5</button>
<button onClick="kalkulacka(6)">6</button>
<button onClick="kalkulacka('-')">−</button>
<br>
<button onClick="kalkulacka(1)">1</button>
<button onClick="kalkulacka(2)">2</button>
<button onClick="kalkulacka(3)">3</button>
<button onClick="kalkulacka('+')">+</button>
<br>
<button onClick="kalkulacka('.')">,</button>
<button onClick="kalkulacka(0)">0</button>
<button onClick="kalkulacka('=')">=</button>
<button onClick="kalkulacka('⌫')">⌫</button>
</body>
</html>
<script>
// "boxik" here just represents that input field
const boxik = document.getElementById("vysledek");
function kalkulacka(x) {
if (x == "C") {
//This clears whole input
boxik.value = "";
} else if (x == "⌫") {
//This removes last digit
boxik.value = boxik.value.substring(0, boxik.value.length-1);
} else if (x == "=") {
//Here is our problem, I expect this to check if it was calculated or
//not
if (eval(boxik.value)) {
boxik.value = eval(boxik.value);
} else {
$("#vysledek").css("border-bottom", "2px solid #bd1515");
}
}
//This basically adds all digits, + etc. together
else {
boxik.value += x;
}
}
</script>
这是正在运行的 JSFiddle:https://jsfiddle.net/mg7zmLos/7/
所以基本上今天我从 Electron 开始，我正在开发计算器应用程序，我刚刚硬编码了它，但它可以工作(到目前为止尚未完成)，但我想检查我的计算是否顺利，如果是，那么我只想执行 boxik.value = eval(boxik.value) ，如果它拧紧，则使用 jQuery $("#vysledek").css("将边框设为红色border-bottom", "2pxsolid #bd1515") 但我不知道如何检查它是否拧紧...
最佳答案
去掉 if，而是在 eval 周围放置一个 try/catch，如下所示:
try {
boxik.value = eval(boxik.value);
$("#vysledek").css("border-bottom", "2px solid #5faed0");
}
catch (e) {
$("#vysledek").css("border-bottom", "2px solid #bd1515");
}
关于javascript - if 语句中的 Eval()，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49184784/