Add flatSift function

[aleclarson]

Use flatSift to efficiently flatten an array that may contain falsy values as well as nested arrays.

Example usage

const input = [[1], false, [2, [3]], null, undefined]

flatSift(input)
// => [1, 2, [3]]

flatSift(input, 2)
// => [1, 2, 3]

Preliminary implementation

This implementation is not yet type-safe.

import { isArray } from 'radashi'

export function flatSift(input: any[], depth: number = 1): any[] {
  const output: any[] = [];

  function recurse(item: any, currentDepth: number): void {
    if (isArray(item) && currentDepth > 0) {
      for (const innerItem of item) {
        recurse(innerItem, currentDepth - 1);
      }
    } else if (item) {
      output.push(item);
    }
  }

  for (const item of input) {
    recurse(item, depth);
  }

  return output;
}

Todo

• Add type safety to the implementation.
• Check to see if this is significantly faster than sift(arrays).flat()

Naming

I chose flatSift since this function combines the functionality of flat and sift into a single efficient loop.

Open to other naming suggestions.