Address code review

index.js

@@ -9,6 +9,12 @@ medias = (async function () {
   // This will be replaced by native code on demand.
   const siteSpecificDetector = null
 
+  /**
+   * Returns a Promise that resolves with a boolean argument indicating whether 
+   * the `src` URL could be a blob pointing at a MediaSource object.
+   * @param {string} src
+   * @returns {Promise}
+   */
   async function isMediaSourceObjectURL (src) {
     if (!src || !src.startsWith('blob:')) {
       return false
@@ -18,25 +24,27 @@ medias = (async function () {
     const signal = controller.signal
     let timeout
     const maybeAbortFetch = new Promise(resolve =>
-      timeout = setTimeout(() => resolve(false), 500)
+      timeout = setTimeout(() => { 
+        resolve(false) 
+        controller.abort()
+      }, 500)
     )
 
     return Promise.any([
       new Promise(resolve => {
-        fetch(src, {
-          signal
-        }).then(response => {
-          resolve(false)
-        }).catch(() => {
-          resolve(true)
-        }).finally(() => {
-          clearTimeout(timeout)
-        })
+        fetch(src, { signal })
+        .then(() => false)
+        .catch(() => true)
       }),
       maybeAbortFetch
     ])
   }
 
+  /**
+   * Returns whether given `url` has https protocol.
+   * @param {string} url
+   * @returns {boolean}
+   */
   function isHttpsScheme (url) {
     if (!url || typeof url !== 'string') {
       return false
@@ -57,19 +65,52 @@ medias = (async function () {
     return isHttpsScheme
   }
 
+  /**
+   * Returns absolute path of given `url`. Note that returns null if it's  not
+   * url nor https scheme.
+   * @param {string} url
+   * @returns {?string}
+   */
   function fixUpUrl (url) {
     if (!isHttpsScheme(url)) {
       return null
     }
 
     if (!url.startsWith('https://')) {
       // Fix up relative path to absolute path
-      url = new URL(url, window.location.origin).href
+      url = new URL(url, window.location).href
     }
 
     return url
   }
 
+  /**
+   * MediaItem will be parsed into C++ object representing PlaylistItem in 
+   *       {
+        "detected": boolean,
+        "mimeType": "video" | "audio",
+        "name": string,
+        "pageSrc": url,
+        "pageTitle": string
+        "src": url
+        "thumbnail": url | undefined
+      }
+   * @typedef MediaItem
+   * @type {object}
+   * @property {string} name
+   * @property {"video" | "audio"} mimeType
+   * @property {string} pageSrc - page url
+   * @property {string} pageTitle - page title
+   * @property {string} src - media url
+   * @property {?string} thumbnail - thumbnail url
+   * @property {boolean} detected
+  */
+
+  /**
+   * Get all media items(video or audio) from the given HTMLMediaElement `node`. 
+   * @param {HTMLMediaElement} node
+   * @returns {MediaItem[]}
+   */
   async function getNodeData (node) {
     const src = fixUpUrl(node.src)
     const srcIsMediaSourceObjectURL = await isMediaSourceObjectURL(src)
@@ -93,14 +134,14 @@ medias = (async function () {
     }
 
     const result = {
-      'name': getMediaTitle(node),
+      name: getMediaTitle(node),
       src,
       srcIsMediaSourceObjectURL,
-      'pageSrc': window.location.href,
-      'pageTitle': document.title,
+      pageSrc: window.location.href,
+      pageTitle: document.title,
       mimeType,
-      'duration': getMediaDurationInSeconds(node),
-      'detected': true
+      duration: getMediaDurationInSeconds(node),
+      detected: true
     }
 
     if (src) {
@@ -126,14 +167,10 @@ medias = (async function () {
     return sources
   }
 
-  function getAllVideoElements () {
-    return document.querySelectorAll('video')
-  }
-
-  function getAllAudioElements () {
-    return document.querySelectorAll('audio')
-  }
-
+  /**
+   * Returns thumbnail url from this page.
+   * @returns {?url}
+   */
   function getThumbnail () {
     const isThumbnailValid = (thumbnail) => { return thumbnail && thumbnail !== '' }
 
@@ -145,6 +182,11 @@ medias = (async function () {
     return fixUpUrl(thumbnail)
   }
 
+  /**
+   * Returns title of media `node`
+   * @param {HTMLMediaElement} node
+   * @returns {?string}
+   */
   function getMediaTitle (node) {
     const isTitleValid = (title) => { return title && title !== '' }
 
@@ -158,6 +200,11 @@ medias = (async function () {
     return title
   }
 
+  /**
+   * Returns the author of given media `node`
+   * @param {HTMLMediaElement} node
+   * @returns {?string}
+   */
   function getMediaAuthor (node) {
     // TODO(sko) Get metadata of author in more general way
     let author = null
@@ -167,6 +214,11 @@ medias = (async function () {
     return author
   }
 
+  /**
+   * Returns duration of given media `node` in seconds 
+   * @param {HTMLMediaElement} node
+   * @returns {number}
+   */
   function getMediaDurationInSeconds (node) {
     const clampDuration = (value) => {
       if (Number.isFinite(value) && value >= 0) return value
@@ -181,8 +233,8 @@ medias = (async function () {
     return clampDuration(duration)
   }
 
-  const videoElements = getAllVideoElements() ?? []
-  const audioElements = getAllAudioElements() ?? []
+  const videoElements = document.querySelectorAll('video') ?? []
+  const audioElements = document.querySelectorAll('audio') ?? []
   // TODO(sko) These data could be incorrect when there're multiple items.
   // For now we're assuming that the first media is a representative one.
   const thumbnail = getThumbnail()