diff --git a/server/utils/scandir.js b/server/utils/scandir.js
index 59a0c2427..7148ef06a 100644
--- a/server/utils/scandir.js
+++ b/server/utils/scandir.js
@@ -149,16 +149,16 @@ module.exports.buildLibraryFile = buildLibraryFile
 function getBookDataFromDir(relPath, parseSubtitle = false) {
   const splitDir = relPath.split('/')
 
-  var folder = splitDir.pop() // Audio files will always be in the directory named for the title
-  var series = splitDir.length > 1 ? splitDir.pop() : null // If there are at least 2 more directories, next furthest will be the series
-  var author = splitDir.length > 0 ? splitDir.pop() : null // There could be many more directories, but only the top 3 are used for naming /author/series/title/
+  const titleFolder = splitDir.pop() // Audio files will always be in the directory named for the title
+  const series = splitDir.length > 1 ? splitDir.pop() : null // If there are at least 2 more directories, next furthest will be the series
+  const author = splitDir.length > 0 ? splitDir.pop() : null // There could be many more directories, but only the top 3 are used for naming /author/series/title/
 
-  // The  may contain various other pieces of metadata, these functions extract it.
-  var [folder, asin] = getASIN(folder)
-  var [folder, narrators] = getNarrator(folder)
-  var [folder, sequence] = series ? getSequence(folder) : [folder, null]
-  var [folder, publishedYear] = getPublishedYear(folder)
-  var [title, subtitle] = parseSubtitle ? getSubtitle(folder) : [folder, null]
+  // Each extractor strips one piece of metadata and returns the remaining folder name.
+  const [afterAsin, asin] = getASIN(titleFolder)
+  const [afterNarrators, narrators] = getNarrator(afterAsin)
+  const [afterSequence, sequence] = series ? getSequence(afterNarrators) : [afterNarrators, null]
+  const [afterYear, publishedYear] = getPublishedYear(afterSequence)
+  const [title, subtitle] = parseSubtitle ? getSubtitle(afterYear) : [afterYear, null]
 
   return {
     title,
@@ -180,8 +180,8 @@ module.exports.getBookDataFromDir = getBookDataFromDir
  * @returns {[string, string]} [folder, narrator]
  */
 function getNarrator(folder) {
-  let pattern = /^(?<title>.*) \{(?<narrators>.*)\}$/
-  let match = folder.match(pattern)
+  const pattern = /^(?<title>.*) \{(?<narrators>.*)\}$/
+  const match = folder.match(pattern)
   return match ? [match.groups.title, match.groups.narrators] : [folder, null]
 }
 
@@ -204,12 +204,12 @@ function getNarrator(folder) {
  */
 function getSequence(folder) {
   // Matches a valid volume string. Also matches a book whose title starts with a 1 to 3 digit number. Will handle that later.
-  let pattern = /^(?<volumeLabel>vol\.? |volume |book )?(?<sequence>\d{0,3}(?:\.\d{1,2})?)(?<trailingDot>\.?)(?: (?<suffix>.*))?$/i
+  const pattern = /^(?<volumeLabel>vol\.? |volume |book )?(?<sequence>\d{0,3}(?:\.\d{1,2})?)(?<trailingDot>\.?)(?: (?<suffix>.*))?$/i
 
   let volumeNumber = null
-  let parts = folder.split(' - ')
+  const parts = folder.split(' - ')
   for (let i = 0; i < parts.length; i++) {
-    let match = parts[i].match(pattern)
+    const match = parts[i].match(pattern)
     // This excludes '101 Dalmations' but includes '101. Dalmations'
     if (match && !(match.groups.suffix && !(match.groups.volumeLabel || match.groups.trailingDot))) {
       volumeNumber = isNaN(match.groups.sequence) ? match.groups.sequence : Number(match.groups.sequence).toString()
@@ -232,10 +232,10 @@ function getSequence(folder) {
  * @returns {[string, string]} [folder, publishedYear]
  */
 function getPublishedYear(folder) {
-  var publishedYear = null
+  let publishedYear = null
 
   const pattern = /^ *\(?([0-9]{4})\)? * - *(.+)/ //Matches #### - title or (####) - title
-  var match = folder.match(pattern)
+  const match = folder.match(pattern)
   if (match) {
     publishedYear = match[1]
     folder = match[2]
@@ -252,7 +252,7 @@ function getPublishedYear(folder) {
  */
 function getSubtitle(folder) {
   // Subtitle is everything after " - "
-  var splitTitle = folder.split(' - ')
+  const splitTitle = folder.split(' - ')
   return [splitTitle.shift(), splitTitle.join(' - ')]
 }
 
@@ -265,7 +265,7 @@ function getSubtitle(folder) {
 function getASIN(folder) {
   let asin = null
 
-  let pattern = /(?: |^)\[([A-Z0-9]{10})](?= |$)/ // Matches "[B0015T963C]"
+  const pattern = /(?: |^)\[([A-Z0-9]{10})](?= |$)/ // Matches "[B0015T963C]"
   const match = folder.match(pattern)
   if (match) {
     asin = match[1]