转换字符串以空格分开单词，并转为小写

/**
 * 转换字符串以空格分开单词，并转为小写
 * Converts `string`, as space separated words, to lower case
 * @param {string} [string=''] The string to convert
 * @returns {string} Returns the lower cased string
 * @example
 * lowerCase('--Foo-Bar--')
 * // => 'foo bar'
 * lowerCase('fooBar')
 * // => 'foo bar'
 * lowerCase('__FOO_BAR__')
 * // => 'foo bar'
 */

import capitalize from "./capitalize" // 我的博客搜索【转换字符串string的首字母为大写】
import words from "./words" //我的博客搜索【拆分字符串string中的词变为数组】
import deburr from "./deburr" //我的博客搜索【转换字符串string中拉丁语-1补充字母和拉丁语扩张字母-A为基本的拉丁字母，并且去除组合变音标记】

/**
 * A specialized version of `reduce` for arrays
 * @param {Array} [array] The array to iteratee over.
 * @param {Function} iteratee The function invoked per iteration
 * @param {*} [accumulator] The initial value
 * @param {boolean} [initAccum] Specify using the first element of `array` as the initial value
 * @returns {*} Returns the accumulated value
 */
function arrayReduce(array, iteratee, accumulator, initAccum) {
  var index = -1,
    length = array == null ? 0 : array.length

  if (initAccum && length) {
    accumulator = array[++index]
  }
  while (++index < length) {
    accumulator = iteratee(accumulator, array[index], index, array)
  }
  return accumulator
}

// Used to match apostrophes.
var rsApos = "['\u2019]"
var reApos = new RegExp(rsApos, "g")

function createCompounder(callback) {
  return function(string) {
    return arrayReduce(words(deburr(string).replace(reApos, "")), callback, "")
  }
}

var lowerCase = createCompounder(function(result, word, index) {
  return result + (index ? " " : "") + word.toLowerCase()
})

export default lowerCase