Function deepMap

src/utils/array.js:867–904

(array, callback, skipIndex = false)

 * @returns {Array} A new array with each element being the result of the callback function.
 */
export function deepMap (array, callback, skipIndex = false) {
  if (array.length === 0) {
    return []
  }

  if (skipIndex) {
    return recursiveMap(array)
  }
  const index = []

  return recursiveMapWithIndex(array, 0)

  function recursiveMapWithIndex (value, depth) {
    if (Array.isArray(value)) {
      const N = value.length
      const result = Array(N)
      for (let i = 0; i < N; i++) {
        index[depth] = i
        result[i] = recursiveMapWithIndex(value[i], depth + 1)
      }
      return result
    } else {
      return callback(value, index.slice(0, depth), array)
    }
  }
  function recursiveMap (value) {
    if (Array.isArray(value)) {
      const N = value.length
      const result = Array(N)
      for (let i = 0; i < N; i++) {
        result[i] = recursiveMap(value[i])
      }
      return result
    } else {
      return callback(value)
    }
  }
}

/**
 * Recursively iterates over each element in a multi-dimensional array and applies a callback function.