javascript - 如何在 javaScript 中获得所有奇数斐波那契值的总和？

Question

我正在解决这个问题Free Code Camp exercise 。

Return the sum of all odd Fibonacci numbers up to and including the passed number if it is a Fibonacci number. The first few numbers of the Fibonacci sequence are 1, 1, 2, 3, 5 and 8, and each subsequent number is the sum of the previous two numbers.

这是我到目前为止所拥有的......

有什么建议吗？

function sumFibs(num) {
    var arr, isFibVal, isEvenVal, sum, i = 0, fibonacci = function (num){
      var a, b, result, fibArr = [1];
        a=0;
        b=1;
        result=b;

        for(var j = 0; j < num; j++){
            result = a + b;
            a = b;
            b = result;
            fibArr.push(result);

       }
      return fibArr;
    },

     isFib = function (val){
     var prev = 0;
     var curr = 1;
     while(prev<=val){
       if(prev == val){
         return true;
       } else {
         return false;
       }
       curr = prev + curr;
       prev = curr - prev;
     }
    },

   isEven = function(someNumber){
         return (someNumber % 2 === 0) ? true : false;
   };

    function sumArray(array) {
      for (
        var
          index = 0,              // The iterator
          length = array.length,  // Cache the array length
          sum = 0;                // The total amount
          index < length;         // The "for"-loop condition
          sum += array[index++]   // Add number on each iteration
      );
      return sum;
    }


      arr = fibonacci(num);
      isFibVal = isFib(num);
      isEvenVal = isEven(num);


    if (isFibVal && !isEvenVal){
        sum  += sumArray(arr);  
}
   return sum;
}

我得到的只是未定义，这似乎很奇怪，因为我认为这部分代码非常酷——使用函数值来检查与 if 语句中的比较。

  arr = fibonacci(num);
          isFibVal = isFib(num);
          isEvenVal = isEven(num);


    if (isFibVal && !isEvenVal){
        sum  += sumArray(arr);  
}

Answer 1

由于您正在通过 FCC，所以我不会直接给您答案，但我会为您提供一些关于在哪里查看的提示:

查看此片段:

for(var j = 0; j < num; j++){
    result = a + b;
    a = b;
    b = result;
    fibArr.push(result);
}

还有这个:

function sumArray(array) {
  for (
    var
      index = 0,              // The iterator
      length = array.length,  // Cache the array length
      sum = 0;                // The total amount
      index < length;         // The "for"-loop condition
      sum += array[index++]   // Add number on each iteration
  );
  return sum;
}

此外，您可能根本不需要此段:

isFibVal = isFib(num);
  isEvenVal = isEven(num);


if (isFibVal && !isEvenVal){
    sum  += sumArray(arr);  

祝你好运。作为一个已经完成大部分类(class)的人，我可以说 Free Code Camp是货真价实的。