Temperature convert in Html css and javascript

[0rahul]

in your tutorial it seems it works but in reality it didnt work why sir i am so desperate with this project and stopped here.
its about conversion for temperature .

[a-shahzad]

in your tutorial it seems it works but in reality it didnt work why sir i am so desperate with this project and stopped here.
its about conversion for temperature .

HTML

<title>temp conv</title>

<form id="tempCalc" onsubmit="calculateTemp(); return false">

    <label for="temp">Enter the temperature to convert</label>
   <br /> <input type="number" name="temp" id="temp">

    <select name="temp_diff" id="temp_diff">
        <option value="cel">°Celcius</option>
        <option value="fah">°Fahrenheit</option>
    </select> <br />

    <input type="submit" name="temp"> <br />

    <span id="resultContainer"></span>
</form>



<script src="script.js"></script>

CSS
@import url(https://fonts.googleapis.com/css2?family=Mulish:wght@300&display=swap);

• {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Mulish", sans-serif;
  }

body {
width: 100vw;
height: 100vh;
background-color: #f8e7af;
display: grid;
place-items: center;
}

form {
background-color: #fab1a0;
padding: 80px;
width: 50%;
margin: 100px auto;
text-align: center;
-webkit-box-shadow: 0 10px 6px -6px #777;
-moz-box-shadow: 0 10px 6px -6px #777;
box-shadow: 0 10px 6px -6px #777;
}

#tempcalc label {
font-size: 30px;
}

#temp {
border: none;
padding: 10px;
height: 40px;
width: 100px;
font-size: 20px;
margin-top: 20px;
}

#temp_diff {
height: 40px;
border: none;
margin-top: 20px;
font-size: 15px;
vertical-align: top;
}

[type="submit"] {
height: 35px;
margin: 20px;
width: 100px;
font-size: 15px;
border: none;
background-color: black;
color: white;
}

#resultContainer {
font-size: 35px;
}

JavaScript
const calculateTemp = () => {
const numberTemp = document.getElementById('temp').value;

const tempSelected = document.getElementById('temp_diff');

const valueTemp = tempSelected.options[tempSelected.selectedIndex].value;

const celToFah = (cel) => {
    let fahrenheit = Math.round(cel * 9/5 + 32);
    return fahrenheit;
}

const fahToCel = (fah) => {
    let celcius = Math.round((fah - 32) * 5/9);
    return celcius;
}

let result;

if(valueTemp == 'cel') {
    result = celToFah(numberTemp);
    document.getElementById('resultContainer').innerHTML = `= ${result}°Fahrenheit`;
}
    else {
        result = fahToCel(numberTemp);
    document.getElementById('resultContainer').innerHTML = `= ${result}°Celcius`;
    }

}