如何从 JS 中通过此函数运行的数组编号元素中删除“-”？

Question

I'm using this function below to sum "columns" of a 2D Array, but some elements contain '-' and I haven't been able to handle it:

I've tried Number(num) or typeof num === 'number' , but still...

 const arr = [ ['-', 2, 21], [1, '-', 4, 54], [5, 2, 2], [11, 5, 3, 1] ]; const sumArray = (array) => { const newArray = []; array.forEach(sub => { sub.forEach((num, index) => { if(newArray[index]){ newArray[index] += num; }else{ newArray[index] = num; } }); }); return newArray; } console.log(sumArray(arr))

Answer 1

You could use map and reduce to achieve this as well.

const arr = [
  ['-', 2, 21],
  [1, '-', 4, 54],
  [5, 2, 2],
  [11, 5, 3, 1],
];

const sums = arr.map((sub) =>
  sub.reduce((previous, current) => {
    // check here that the value is a number
    if (typeof current === 'number') {
      return previous + current;
    }

    return previous;
  }, 0)
);

console.log(sums);

// returns [23, 59, 9, 20]

Answer 2

Try:

 const arr = [ ['-', 2, 21], [1, '-', 4, 54], [5, 2, 2], [11, 5, 3, 1] ]; const sumArray = (array) => { const newArray = []; array.forEach(sub => { sub.forEach((num, index) => { if (typeof num == 'number') { if (newArray[index]) { newArray[index] += num; } else { newArray[index] = num; } } }); }); return newArray; } console.log(sumArray(arr))

Here's a more concise solution:

 const arr = [ ['-', 2, 21], [1, '-', 4, 54], [5, 2, 2], [11, 5, 3, 1] ]; const result = arr.map((e, i) => arr.reduce((a, c) => (typeof c[i] == 'number'? a + c[i]: a), 0)) console.log(result)

Answer 3

Using splice() would help remove the - from the array