魔改了一下Butterfly的源代码之后 hexo g 出现如下报错：

TypeError: coverVal.indexOf is not a function
    at Hexo.<anonymous> (E:\Blog\themes\butterfly\scripts\filters\random_cover.js:15:30)
    at Hexo.tryCatcher (E:\Blog\node_modules\bluebird\js\release\util.js:16:23)
    at Hexo.<anonymous> (E:\Blog\node_modules\bluebird\js\release\method.js:15:34)
    at E:\Blog\node_modules\hexo\dist\extend\filter.js:58:67
    at tryCatcher (E:\Blog\node_modules\bluebird\js\release\util.js:16:23)     
    at Object.gotValue (E:\Blog\node_modules\bluebird\js\release\reduce.js:166:18)
    at Object.gotAccum (E:\Blog\node_modules\bluebird\js\release\reduce.js:155:25)
    at Object.tryCatcher (E:\Blog\node_modules\bluebird\js\release\util.js:16:23)
    at Promise._settlePromiseFromHandler (E:\Blog\node_modules\bluebird\js\release\promise.js:547:31)
    at Promise._settlePromise (E:\Blog\node_modules\bluebird\js\release\promise.js:604:18)
    at Promise._settlePromise0 (E:\Blog\node_modules\bluebird\js\release\promise.js:649:10)
    at Promise._settlePromises (E:\Blog\node_modules\bluebird\js\release\promise.js:729:18)
    at _drainQueueStep (E:\Blog\node_modules\bluebird\js\release\async.js:93:12)
    at _drainQueue (E:\Blog\node_modules\bluebird\js\release\async.js:86:9)    
    at Async._drainQueues (E:\Blog\node_modules\bluebird\js\release\async.js:102:5)
    at Immediate.Async.drainQueues [as _onImmediate] (E:\Blog\node_modules\bluebird\js\release\async.js:15:14)
    at processImmediate (internal/timers.js:464:21)

打开 .\themes\butterfly\scripts\filters\random_cover.js 文件如下：

/**
 * Butterfly
 * ramdom cover
 */

'use strict'

hexo.extend.filter.register('before_post_render', data => {
  const imgTestReg = /\.(png|jpe?g|gif|svg|webp)(\?.*)?$/i
  let { cover: coverVal, top_img: topImg } = data

  // Add path to top_img and cover if post_asset_folder is enabled
  if (hexo.config.post_asset_folder) {
    if (topImg && topImg.indexOf('/') === -1 && imgTestReg.test(topImg)) data.top_img = `${data.path}${topImg}`
    if (coverVal && coverVal.indexOf('/') === -1 && imgTestReg.test(coverVal)) data.cover = `${data.path}${coverVal}`
  }

  const randomCoverFn = () => {
    const { cover: { default_cover: defaultCover } } = hexo.theme.config
    if (!defaultCover) return false
    if (!Array.isArray(defaultCover)) return defaultCover
    const num = Math.floor(Math.random() * defaultCover.length)
    return defaultCover[num]
  }

  if (coverVal === false) return data

  // If cover is not set, use random cover
  if (!coverVal) {
    const randomCover = randomCoverFn()
    data.cover = randomCover
    coverVal = randomCover // update coverVal
  }

  if (coverVal && (coverVal.indexOf('//') !== -1 || imgTestReg.test(coverVal))) {
    data.cover_type = 'img'
  }

  return data
})

将文件内容修改为：

/**
 * Butterfly
 * random cover
 */

'use strict'

hexo.extend.filter.register('before_post_render', data => {
  const imgTestReg = /\.(png|jpe?g|gif|svg|webp)(\?.*)?$/i
  let { cover: coverVal, top_img: topImg } = data
  const postAssetFolder = hexo.config.post_asset_folder
  const defaultCover = hexo.theme.config.cover.default_cover

  // Cache random cover if needed
  let randomCover;
  const randomCoverFn = () => {
    if (!defaultCover) return false
    if (!Array.isArray(defaultCover)) return defaultCover
    if (!randomCover) {
      const num = Math.floor(Math.random() * defaultCover.length)
      randomCover = defaultCover[num]
    }
    return randomCover
  }

  // Add path to top_img and cover if post_asset_folder is enabled
  if (postAssetFolder) {
    if (typeof topImg === 'string' && topImg.indexOf('/') === -1 && imgTestReg.test(topImg)) {
      data.top_img = `${data.path}${topImg}`
    }
    if (typeof coverVal === 'string' && coverVal.indexOf('/') === -1 && imgTestReg.test(coverVal)) {
      data.cover = `${data.path}${coverVal}`
    }
  }

  if (coverVal === false) return data

  // If cover is not set, use random cover
  if (!coverVal) {
    const randomCover = randomCoverFn()
    data.cover = randomCover
    coverVal = randomCover // update coverVal
  }

  if (typeof coverVal === 'string' && (coverVal.indexOf('//') !== -1 || imgTestReg.test(coverVal))) {
    data.cover_type = 'img'
  }

  return data
})

做的改动有：

  1. 变量声明优化：将 postAssetFolder 和 defaultCover 单独提取出来，避免多次访问配置。
  2. 缓存随机封面：添加了 randomCover 变量，用于缓存随机封面，避免重复计算。
  3. 类型检查：在使用 indexOf 之前，增加了对 topImg 和 coverVal 的类型检查，确保它们是字符串。
  4. 逻辑优化：在 randomCoverFn 中，增加了对 randomCover 的缓存检查，避免多次随机选择。