base10toX.html

<!DOCTYPE html>
<html>
<body>
<style>
    body{
        background:#111;
        font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
        color:#ddd;
    }
</style>
<h2>From 10 base to X base number - program by: Kun Attila</h2>
<form>
    <table>
        <tr>
            <td><label for="num">Number (0 up to 2<sup>64</sup>-1):</label></td>
            <td><input type="number" id="num" name="num" oninput="calculate(this.value, document.getElementById('numSys').value);"></td>
        </tr>
        <tr>
            <td><label for="numSys">Number System(2-36):</label></td>
            <td><input type="number" id="numSys" name="numSys" oninput="calculate(document.getElementById('num').value, this.value);"></td>
        </tr>
        <tr>
            <td><label for="res">Result:</label></td>
            <td><span id="res">Fill the inputs</span></td>
        </tr>
    </table>
</form>
<script>
const resTXT = document.getElementById("res");
function calculate(numb, numbSys){
    
    if (numb > (Math.pow(2,64)-1)){
        resTXT.innerHTML = "This program doesn't allow numbers greater than 2<sup>64</sup>-1";
    }
	else if (numb == 0){
		resTXT.innerHTML = "0";
	}
	else if (numb < 1){
		 resTXT.innerHTML = "Enter a number greater than or equal to 0";	
	}
    else if (numbSys > 36 || numbSys < 2)
    {
        resTXT.innerHTML = "Wrong number system entered";
    }
    else
    {
        let result = [];
        let numbers = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        let p = 0;
        while (numb > 0)
        {
            result[p] = numbers[numb % numbSys];
            numb = Math.floor(numb/numbSys);
            p++;
        }
        let output = '';
        for (let i = p - 1; i > -1; i--)
        {
            output += result[i];
        }
        resTXT.innerHTML = output;
    }

}

</script>

</body>
</html>