Javascript 挑战：循环 - 多个条件 - 卡住了，无法弄清楚

Question

我在函数和执行上下文上完成了这个模块 - 所有问题都进行得很顺利，但有一个挑战我花了很多时间但仍然无法解决。任何帮助将不胜感激。谢谢

挑战问题说： 编写一个函数addingAllTheWeirdStuff，将array2中所有奇数的和与array1中10以下的每个元素相加。

同样，addingAllTheWeirdStuff 也应该将 array2 中所有偶数的总和与 array1 中超过 10 的元素相加。

奖励：如果 array2 中的任何元素大于 20，则将 array1 中的每个元素加 1。

// Uncomment these to check your work!
// console.log(addingAllTheWeirdStuff([1, 3, 5, 17, 15], [1, 2, 3, 4, 5])); // expected log [10, 12, 14, 23, 21]
// console.log(addingAllTheWeirdStuff([1, 3, 5, 17, 15, 1], [1, 2, 3, 4, 5, 22])); // expected log [11, 13, 15, 46, 44, 11]

// my attempt so far:
function addingAllTheWeirdStuff(array1, array2) {
  // ADD CODE HERE
  let result = []
  for (let i = 0; i < array2.length; i++) {
    if (array2[i] > 20) {
      result = array1[i] += 1
    }
  }
  for (let i = 0; i < array2.length; i++) {
    if (array2[i] % 2 === 0 && array1[i] > 10) {
      result = array1[i] + array2[i]
    }
  }
  for (let i = 0; i < array2.length; i++) {
    if (array2[i] % 2 !== 0 && array1[i] < 10) {
      result = array1[i] + array2[i]
    }
  }
  return result
}

Answer 1

您可以使用reduce 和map 数组方法以及三元运算符轻松实现此目的：

const array1 = [1, 3, 5, 17, 15];
const array2 = [1, 2, 3, 4, 5];

function addingAllTheWeirdStuff(array1, array2) {

    const oddSum = array2.reduce((sum, current) => current % 2 ? current + sum : 0 + sum, 0)
    const oddEven = array2.reduce((sum, current) => current % 2 == 0 ? current + sum : 0 + sum, 0)

    return array1.map(num => num < 10 ? num + oddSum : num + oddEven)

}

console.log(addingAllTheWeirdStuff(array1, array2))

Answer 2

如果您将挑战分解成更小的部分，您可以更好地解构它并提出您的解决方案。

这就是我所做的......我将很快添加更多的 cmets 并提供更多解释

我选择继续使用循环，因为我认为这是挑战的重点（练习循环、多个条件等） - 换句话说，我选择不故意使用map / reduce，但如果允许的话，使用@charmful0x 的答案，因为它会减少代码:)

// function to get sum of all odd numbers in array
function getSumOfAllOddNumbersInArray( elementArray ){
  var sumOfOddNumbers = 0;
  
  for (let i = 0; i < elementArray.length; i++) {
    // use remainder operator to find out if element is odd or not
    if (elementArray[i] % 2 !== 0 ) {
      sumOfOddNumbers += elementArray[i];
    }
  }
  
  return sumOfOddNumbers;
}

// function to get sum of all EVEN numbers in array
function getSumOfAllEvenNumbersInArray( elementArray ){
  var sumOfEvenNumbers = 0;
  
  for (let i = 0; i < elementArray.length; i++) {
    // use remainder operator to find out if element is odd or not
    if (elementArray[i] % 2 === 0 ) {
      sumOfEvenNumbers += elementArray[i];
    }
  }
  
  return sumOfEvenNumbers;
}

// Return true if there is at least one element in array that is greater than 20
function hasElementOverTwenty( elementArray ){
  for (let i = 0; i < elementArray.length; i++) {
    if (elementArray[i] > 20 ) {
      // no need to keep looping, we found one - exit function
      return true;
    }
  }
  
  return false;
}


function addingAllTheWeirdStuff( firstArray, secondArray ){
  var sumOfOddNumbersInArray = getSumOfAllOddNumbersInArray( secondArray );
  var sumOfEvenNumbersInArray = getSumOfAllEvenNumbersInArray( secondArray );
  var needToAddOne = hasElementOverTwenty( secondArray );
    
  for (let i = 0; i < firstArray.length; i++) {
    // Challenge One
    if (firstArray[i] < 10) {
      firstArray[i] = firstArray[i] + sumOfOddNumbersInArray;       
      
    } else if (firstArray[i] > 10) {
    // Challenge Two
      firstArray[i] = firstArray[i] + sumOfEvenNumbersInArray;       
    }
    
    // bonus
    if( needToAddOne ){
      firstArray[i]++;
    }   
  }
  
  return firstArray;
}

// Uncomment these to check your work!
console.log(addingAllTheWeirdStuff([1, 3, 5, 17, 15], [1, 2, 3, 4, 5])); 
console.log('expected:' + [10, 12, 14, 23, 21] );
console.log(addingAllTheWeirdStuff([1, 3, 5, 17, 15, 1], [1, 2, 3, 4, 5, 22]));
console.log('expected:' + [11, 13, 15, 46, 44, 11] );

Challenge question says: Write a function addingAllTheWeirdStuff which adds the sum of all the odd numbers in array2 to each element under 10 in array1.

Similarly, addingAllTheWeirdStuff should also add the sum of all the even numbers in array2 to those elements over 10 in array1.

BONUS: If any element in array2 is greater than 20, add 1 to every element in array1.