如何将Java代码写入JavaScript

Question

我正在努力将Java代码转换为javascript。为此，例如，我正在将public静态int primesolution转换为函数primesolution。我不太知道我是否在转换它的正确轨道上。我被困在公共静态空main（String[]args）中。如何将此函数转换为Javascript。非常感谢任何帮助。

import java.lang.Math;
public class EvaluateDivisors {

     public static void main(String[] args) {
        try {
            long a = Long.parseLong(args[0]);
            long b = Long.parseLong(args[1]);
            int k = Integer.parseInt(args[2]);

            if (a <= 1 || b <= a) {
                error("Error: must have 1 < A < B");
            }
            if (k <= 0 || k % 2 == 0) {
                error("Error: K must be a positive odd number");
            }
            System.out.println(solution(a, b, k));
        } catch (IndexOutOfBoundsException e) {
            error("Usage: EvaluateDivisors A B K");
        } catch (NumberFormatException e) {
            error("Error: arguments must be integers");
        }
    }


    private static int solution(long a, long b, int k) {


        if (prime(k)) {
            return primeSolution(a, b, k);
        }
        int result = 0;

         for (long n = (long) Math.sqrt(a); n*n <= b; n++) {

           int divisors = 3;


            for (long m = 2; m < n && divisors <= k; m++) {
                if (n*n % m == 0) {
                    divisors += 2;
                }
            }
            if (divisors == k) {
                result++;
            }
        }
        return result;
    }


      private static int primeSolution(long a, long b, int k) {
        int result = 0;


        int n = 2;
        while (Math.pow(n, k - 1) < a) {
            n++;
        }
        while (Math.pow(n, k - 1) <= b) {
            if (prime(n++)) {
                result++;
            }
        }
        return result;
    }


    private static boolean prime(int n) {

        for (int m = 2; m <= Math.sqrt(n); m++) {
            if (n % m == 0) {
                return false;
            }
        }
        return true;
    }
    private static void error(String message) {
        System.err.println(message);
        System.exit(1);
    }

}

我用JavaScript转换的代码

function EvaluateDivisors {

    function main(String[] args) {
        try {
            long a = Long.parseLong(args[0]);
            long b = Long.parseLong(args[1]);
            int k = Integer.parseInt(args[2]);

            if (a <= 1 || b <= a) {
                error("Error: must have 1 < A < B");
            }
            if (k <= 0 || k % 2 == 0) {
                error("Error: K must be a positive odd number");
            }
            System.out.println(solution(a, b, k));
        } catch (IndexOutOfBoundsException e) {
            error("Usage: EvaluateDivisors A B K");
        } catch (NumberFormatException e) {
            error("Error: arguments must be integers");
        }
    }


    function solution(long a, long b, int k) {

        if (prime(k)) {
            return primeSolution(a, b, k);
        }
        int result = 0;

        for (long n = (long) Math.sqrt(a); n*n <= b; n++) {

            int divisors = 3;

            for (long m = 2; m < n && divisors <= k; m++) {
                if (n*n % m == 0) {
                    divisors += 2;
                }
            }
            if (divisors == k) {
                result++;
            }
        }
        return result;
    }

    function primeSolution(long a, long b, int k) {
      int result = 0;

       int n = 2;
      while (Math.pow(n, k - 1) < a) {
          n++;
      }
      while (Math.pow(n, k - 1) <= b) {
          if (prime(n++)) {
              result++;
          }
      }
      return result;
  }


        function prime(int n) {
        for (int m = 2; m <= Math.sqrt(n); m++) {
            if (n % m == 0) {
                return false;
            }
        }
        return true;
    }

    function error(String message) {
        console.log(message);
        System.exit(1);
    }

}

Answer 1

您应该使用事件侦听器进行文档加载（它将在加载html后执行其内容）：

document.addEventListener("DOMContentLoaded", function(){
    // Your main() code here
});

or change it to classic function with parameters like this:

function mainFunction(yourVar)

然后，JS是动态类型化语言，所以必须使用int、long、string等的通用变量istead。

然后，您可以将其他函数与上面的函数并排放置，因此最终的javascript代码如下所示：

// Use function like this:
// function yourFunction(parameter1, parameter2, ...) {
// or use document DOMContentLoaded event listener:
function yourFunction(a, b, k) {
    try {
        if (a <= 1 || b <= a) {
            error("Error: must have 1 < A < B");
        }
        if (k <= 0 || k % 2 == 0) {
            error("Error: K must be a positive odd number");
        }
        console.log(solution(a, b, k));
    } catch(e) {
        error("Usage: EvaluateDivisors A B K");
    }
};

function solution(a, b, k) {  
    if (prime(k)) {
        return primeSolution(a, b, k);
    }
    var result = 0;

    for (var n = Math.sqrt(a); n * n <= b; n++) {

        var divisors = 3;

        for (var m = 2; m < n && divisors <= k; m++) {
            if (n * n % m == 0) {
                divisors += 2;
            }
        }
        if (divisors == k) {
            result++;
        }
    }
    return result;
}

function primeSolution(a, b, k) {
    var result = 0;

    var n = 2;
    while (Math.pow(n, k - 1) < a) {
        n++;
    }
    while (Math.pow(n, k - 1) <= b) {
        if (prime(n++)) {
            result++;
        }
    }
    return result;
}


function prime(n) {
    for (var m = 2; m <= Math.sqrt(n); m++) {
        if (n % m == 0) {
            return false;
        }
    }
    return true;
}

function error(message) {
    console.log(message);
}

我建议您使用JavaScript验证程序：http://esprima.org/demo/validate.html

然后调试浏览器控制台（在windows上，您可以使用F12在几乎任何浏览器中打开它）

而要在w3学校上搜索帮助，其令人敬畏的帮助来源：https://www.w3schools.com/js/