CODEWITHSUNDEEP
javascripthtmlelectronevalcalculator
Ejdrien
Ejdrien

Reputation: 2900

Eval() in if statement

HTML & 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('/')">&#247;</button>
        <br>
      <button onClick="kalkulacka(7)">7</button>
      <button onClick="kalkulacka(8)">8</button>
      <button onClick="kalkulacka(9)">9</button>
      <button onClick="kalkulacka('*')">&#215;</button>
        <br>
      <button onClick="kalkulacka(4)">4</button>
      <button onClick="kalkulacka(5)">5</button>
      <button onClick="kalkulacka(6)">6</button>
      <button onClick="kalkulacka('-')">&#8722;</button>
        <br>
      <button onClick="kalkulacka(1)">1</button>
      <button onClick="kalkulacka(2)">2</button>
      <button onClick="kalkulacka(3)">3</button>
      <button onClick="kalkulacka('+')">&#43;</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>

Here is working JSFiddle: https://jsfiddle.net/mg7zmLos/7/

So basically today I started with Electron and I'm working on calculator app which I just hard-coded, but it works (it isn't completed so far) but I want to check if my calculation went good or not, if yes then I just want to do boxik.value = eval(boxik.value) and if it screws then make my border red using jQuery $("#vysledek").css("border-bottom", "2px solid #bd1515") but I don't know how to check if it screwed or not...

Upvotes: 0

Views: 704

Answers (1)

kshetline
kshetline

Reputation: 13672

Get rid of the if, instead put a try/catch around the eval like this:

    try {
      boxik.value = eval(boxik.value);
      $("#vysledek").css("border-bottom", "2px solid #5faed0");
    }
    catch (e) {
      $("#vysledek").css("border-bottom", "2px solid #bd1515");
    }

Upvotes: 1

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