javascript - 映射二维数组的元素，忽略最后一个子数组

Question

假设有这个矩阵:

myArray = [["a", 6, 5.54, "b"],
           ["xxx", 65.5, 45],
           [343, "abc", 0.09]];

我的目标是计算每个子数组的总和，但忽略最后一个子数组，在本例中为[343, "abc", 0.09]。另外，忽略字符串值。

我设法对所有子数组执行此操作，它看起来像这样:

myArray = [["a", 6, 5.54, "b"],
           ["xxx", 65.5, 45],
           [343, "abc", 0.09]];

result = myArray.map(a => a.reduce((s, v) => s + (+v || 0), 0));
console.log(result)

不知道要添加哪个条件才能忽略最后一个子数组。

有什么想法吗？

Answer 1

使用函数slice(0, -1)。

The slice() method returns a shallow copy of a portion of an array into a new array object selected from begin to end (end not included). The original array will not be modified.

Second param: A negative index can be used, indicating an offset from the end of the sequence. slice(2,-1) extracts the third element through the second-to-last element in the sequence.

var myArray = [
  ["a", 6, 5.54, "b"],
  ["xxx", 65.5, 45],
  [343, "abc", 0.09]
];

var result = myArray.slice(0, -1).map(a => a.reduce((s, v) => s + (+v || 0), 0));

console.log(result);