分解质因数法求最大公约数(javascrip实现)

<!DOCTYPE html>

<html>

<head lang="en">

    <meta charset="UTF-8">

    <title></title>

    <script type="text/javascript" src="jquery.min.js"></script>

    <script type="text/javascript">

        //判断是否为质数------------------------------------------------------

        function isPrime(n) {

            for (var i = n - 1; i > 1; i--) {

                if (n % i == 0) {

                    return false;

                }

            }

            return true;

        }

        //        ---------------------------------------------------

        //求出一个数(非质数)的质因数--------------------------------------------------------

        function primeArray(n, array) {

            array = new Array();

            for (var i = 2; i < n; i++) {

                //是否为质数

                if (isPrime(i)) {

                    var temp_R = n % i;//余数

                    var temp_c = n / i;//商

                    //是否整除

                    if (temp_R == 0) {

                        array.push(i);

                        if (!isPrime(temp_c)) {

                            //商不为质数

                            array = array.concat(primeArray(temp_c, array));

                        } else {

                            array.push(temp_c);

                        }

                        break;

                    }

                }

            }

            return array;

        }

        //            查找两个数组的相同部分-----------------------------------

        function findSamePart(a, b) {

            var temp = new Array();

            for (var i = 0; i < a.length; i++) {

                for (var j = 0; j < b.length; j++) {

                    if (a[i] == b[j]) {

                        temp.push(a[i]);

                        a.splice(i, 1);

                        b.splice(i, 1);

                        i =0;

                        continue;

                    }

                }

            }

            return temp;

        }

        //---------------------------------------------------

        //        分解质因数求最大公因数-----------------

        function gcd(a, b) {

            if (isPrime(a) || isPrime(b)) {

                return 1;

            }

            var a = parseInt($("#a").val());

            var b = parseInt($("#b").val());

            var a_array = new Array();

            var b_array = new Array();

            var a_array = primeArray(a, a_array);

            var b_array = primeArray(b, b_array);

            var temp = findSamePart(a_array, b_array);

            var sum = 1;

            for (var i = 0; i < temp.length; i++) {

                sum = sum * temp[i];

            }

            return sum;

        }

    </script>

</head>

<body>

<div>

    <h1>分解质因数法</h1>

    <input type="number" id="a" placeholder="整数a"></br>

    <input type="number" id="b" placeholder="整数b">

    </br>

    <input type="button" value="求最大公约数" onclick="demo();">

    <script type="text/javascript">

        function demo() {

            var a = $("#a").val();

            var b = $("#b").val();

            alert(a+"和"+b+"的最大公约数是"+gcd(a, b));

        }

    </script>

</div>

</body>

</html>