JavaScript-Programs/prime-number.html at master · softwaredeveloperhub01/JavaScript-Programs · GitHub

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<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

<body>
    <form name="numbers">
        Beginning Number: <input type="text" name="firstNum" />
        End Number: <input type="text" name="secondNum" />
        <input type="button" value="Find Prime Numbers" onclick="calcPrimeNumber()" />

    </form>
    <div id="output_content">
    </div>

    <script type="text/javascript">

        function calcPrimeNumber() {

            var beginNum = parseInt(document.numbers.firstNum.value);
            var endNum = parseInt(document.numbers.secondNum.value);
            var primeNumbs = new Array();
            var ctr = beginNum;
            while (ctr <= endNum) {
                if (isPrime(ctr) == true) {
                    primeNumbs[primeNumbs.length] = ctr;
                }
                ctr = ctr + 1;
            }
            if (primeNumbs.length == 0) {
                document.getElementById('output_content').innerHTML = "There were no prime no within the range.";
            }
            else {
                outputPrimeNums(primeNumbs);
            }
        }
        function isPrime(num) {
            var flag = true;
            for (var i = 2; i <= Math.ceil(num / 2); i++) {
                if ((num % i) == 0) {
                    flag = false;
                    break;
                }
            }
            return flag;
        }

        function outputPrimeNums(primes) {
            var html = "<h2>Prime Numbers</h2>";
            for (i = 0; i < primes.length; i++) {
                html += primes[i] + "<br/>";
            }
            document.getElementById('output_content').innerHTML = html;
        }

    </script>

</body>

</html>