将Javascript数组元素拆分为指定索引处的块

问题描述

我有一个像这样的数组

const arr = [3,6,9,12,18,21,24,27,33,36];

我想将数组 arr 分成12、21和33的块。就是索引3、5和8。我想生成另一个数组块，如下所示。.

I want the array arr split into chunks at 12, 21 and 33. That is at the index 3, 5, and 8. I want to produce another array chunks looking like this..

const chunks = [[3,6,9,12],[18,21],[24,27,33],[36]];

我在这里看到的解决方案基本上将数组拆分为n个块。基本上我想在几个（指定的）索引处拆分数组。

The solutions I have seen here basically split arrays into 'n' chunks. Basically I want to split at arrays at several (specified) indexes.

我不介意underscore.js / lodash解决方案。谢谢

I do not mind an underscore.js/lodash solution. Thanks

推荐答案

您可以使用 reduceRight 并确定要拆分的元素。由于您提供的是子数组的 last 值而不是 first 的值，因此从右向左移动实际上更容易一些，因此我使用了 reduceRight 而不是 red 。

You could use reduceRight and decide which elements to split at. Since you’re providing the last values of a sub-array rather than the first ones, going from right to left is actually a bit easier, hence I use a reduceRight rather than a reduce.

const arr = [3, 6, 9, 12, 18, 21, 24, 27, 33, 36],
  splitValues = [12, 21, 33],
  chunks = arr.reduceRight((result, value) => {
    result[0] = result[0] || [];

    if (splitValues.includes(value)) {
      result.unshift([value]);
    } else {
      result[0].unshift(value);
    }

    return result;
  }, []);

console.log(chunks);

.as-console-wrapper { max-height: 100% !important; top: 0; }

const arr = [3, 6, 9, 12, 18, 21, 24, 27, 33, 36],
  splitIndexes = [3, 5, 8],
  chunks = arr.reduceRight((result, value, index) => {
    result[0] = result[0] || [];

    if (splitIndexes.includes(index)) {
      result.unshift([value]);
    } else {
      result[0].unshift(value);
    }

    return result;
  }, []);

console.log(chunks);

.as-console-wrapper { max-height: 100% !important; top: 0; }

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