diff --git a/src/js/dashboard.js b/src/js/dashboard.js
index 6604c67..234490f 100644
--- a/src/js/dashboard.js
+++ b/src/js/dashboard.js
@@ -519,7 +519,7 @@ page.getUploads = (params = {}) => {
     params.pageNum = 0
   }
 
-  const url = params.album !== undefined
+  const url = typeof params.album !== 'undefined'
     ? `api/album/${params.album}/${params.pageNum}`
     : `api/uploads/${params.pageNum}`
 
@@ -673,9 +673,7 @@ page.getUploads = (params = {}) => {
     let unselected = false
 
     const showOriginalNames = page.views[page.currentView].originalNames
-    const hasExpiryDateColumn = files.some(file => {
-      return file.expirydate !== undefined
-    })
+    const hasExpiryDateColumn = files.some(file => typeof file.expirydate !== 'undefined')
 
     for (let i = 0; i < files.length; i++) {
       // Build full URLs
@@ -727,7 +725,7 @@ page.getUploads = (params = {}) => {
         files[i].appendix = files[i].userid
           ? users[files[i].userid] || ''
           : ''
-      } else if (params.album === undefined) {
+      } else if (typeof params.album === 'undefined') {
         files[i].appendix = files[i].albumid
           ? albums[files[i].albumid] || ''
           : ''
@@ -754,7 +752,7 @@ page.getUploads = (params = {}) => {
         div.className = 'image-container column'
         div.dataset.id = upload.id
 
-        if (upload.thumb !== undefined) {
+        if (typeof upload.thumb !== 'undefined') {
           div.innerHTML = `<a class="image" href="${upload.file}" target="_blank"><img alt="${upload.name}" data-src="${upload.thumb}"/></a>`
         } else {
           div.innerHTML = `<a class="image" href="${upload.file}" target="_blank"><h1 class="title">${upload.extname || 'N/A'}</h1></a>`
@@ -812,7 +810,7 @@ page.getUploads = (params = {}) => {
                 <th class="controls"><input id="selectAll" class="checkbox" type="checkbox" title="Select all" data-action="select-all"></th>
                 <th title="Key: name">File name</th>
                 ${showOriginalNames ? '<th title="Key: original">Original name</th>' : ''}
-                ${params.album === undefined ? `<th title="Key: ${params.all ? 'userid">User' : 'albumid">Album'}</th>` : ''}
+                ${typeof params.album === 'undefined' ? `<th title="Key: ${params.all ? 'userid">User' : 'albumid">Album'}</th>` : ''}
                 ${allAlbums ? '<th title="Key: albumid">Album</th>' : ''}
                 <th title="Key: size">Size</th>
                 ${params.all ? '<th title="Key: ip">IP</th>' : ''}
@@ -840,7 +838,7 @@ page.getUploads = (params = {}) => {
           <td class="controls"><input type="checkbox" class="checkbox" title="Select" data-index="${i}" data-action="select"${upload.selected ? ' checked' : ''}></td>
           <th class="name"><a href="${upload.file}" target="_blank" title="${upload.file}">${upload.name}</a></th>
           ${showOriginalNames ? `<th class="originalname" title="${upload.original}">${upload.original}</th>` : ''}
-          ${params.album === undefined ? `<th class="appendix">${upload.appendix}</th>` : ''}
+          ${typeof params.album === 'undefined' ? `<th class="appendix">${upload.appendix}</th>` : ''}
           ${allAlbums ? `<th class="album">${upload.albumid ? (albums[upload.albumid] || '') : ''}</th>` : ''}
           <td class="prettybytes">${upload.prettyBytes}</td>
           ${params.all ? `<td class="ip">${upload.ip || ''}</td>` : ''}
@@ -3021,13 +3019,13 @@ window.addEventListener('DOMContentLoaded', () => {
     Object.defineProperty(Object, 'assign', {
       value: function assign (target, varArgs) { // .length of function is 2
         'use strict'
-        if (target === null || target === undefined) {
+        if (target === null || typeof target === 'undefined') {
           throw new TypeError('Cannot convert undefined or null to object')
         }
         const to = Object(target)
         for (let i = 1; i < arguments.length; i++) {
           const nextSource = arguments[i]
-          if (nextSource !== null && nextSource !== undefined) {
+          if (nextSource !== null && typeof nextSource !== 'undefined') {
             for (const nextKey in nextSource) {
               // Avoid bugs when hasOwnProperty is shadowed
               if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) {
diff --git a/src/js/home.js b/src/js/home.js
index 5ef0da6..b5a8f7d 100644
--- a/src/js/home.js
+++ b/src/js/home.js
@@ -399,7 +399,7 @@ page.prepareDropzone = () => {
         }
 
         // Attach necessary data for initial upload speed calculation
-        if (xhr._uplSpeedCalc === undefined) {
+        if (typeof xhr._uplSpeedCalc === 'undefined') {
           xhr._uplSpeedCalc = {
             lastSent: 0,
             data: [{ timestamp: Date.now(), bytes: 0 }]
@@ -947,9 +947,9 @@ page.prepareUploadConfig = () => {
 
     let value
     if (!conf.disabled) {
-      if (conf.value !== undefined) {
+      if (typeof conf.value !== 'undefined') {
         value = conf.value
-      } else if (conf.number !== undefined) {
+      } else if (typeof conf.number !== 'undefined') {
         const parsed = parseInt(localStorage[lsKeys[key]])
         if (!isNaN(parsed) && parsed <= conf.number.max && parsed >= conf.number.min) {
           value = parsed
@@ -969,9 +969,9 @@ page.prepareUploadConfig = () => {
       // otherwise pass value to global page object
       if (typeof conf.valueHandler === 'function') {
         conf.valueHandler(value)
-      } else if (value !== undefined) {
+      } else if (typeof value !== 'undefined') {
         page[key] = value
-      } else if (fallback[key] !== undefined) {
+      } else if (typeof fallback[key] !== 'undefined') {
         page[key] = fallback[key]
       }
     }
@@ -985,7 +985,7 @@ page.prepareUploadConfig = () => {
       for (let j = 0; j < conf.select.length; j++) {
         const opt = conf.select[j]
         const selected = (value && (opt.value === String(value))) ||
-          (value === undefined && opt.value === 'default')
+          (typeof value === 'undefined' && opt.value === 'default')
         opts.push(`
           <option value="${opt.value}"${selected ? ' selected' : ''}>
             ${opt.text}${opt.value === 'default' ? ' (default)' : ''}
@@ -1004,10 +1004,10 @@ page.prepareUploadConfig = () => {
       control.className = 'input is-fullwidth'
       control.type = 'number'
 
-      if (conf.number.min !== undefined) control.min = conf.number.min
-      if (conf.number.max !== undefined) control.max = conf.number.max
+      if (typeof conf.number.min !== 'undefined') control.min = conf.number.min
+      if (typeof conf.number.max !== 'undefined') control.max = conf.number.max
       if (typeof value === 'number') control.value = value
-      else if (conf.number.default !== undefined) control.value = conf.number.default
+      else if (typeof conf.number.default !== 'undefined') control.value = conf.number.default
     }
 
     let help
@@ -1020,16 +1020,16 @@ page.prepareUploadConfig = () => {
       help = 'This option is currently not configurable.'
     } else if (typeof conf.help === 'string') {
       help = conf.help
-    } else if (conf.help === true && conf.number !== undefined) {
+    } else if (conf.help === true && typeof conf.number !== 'undefined') {
       const tmp = []
 
-      if (conf.number.default !== undefined) {
+      if (typeof conf.number.default !== 'undefined') {
         tmp.push(`Default is ${conf.number.default}${conf.number.suffix || ''}.`)
       }
-      if (conf.number.min !== undefined) {
+      if (typeof conf.number.min !== 'undefined') {
         tmp.push(`Min is ${conf.number.min}${conf.number.suffix || ''}.`)
       }
-      if (conf.number.max !== undefined) {
+      if (typeof conf.number.max !== 'undefined') {
         tmp.push(`Max is ${conf.number.max}${conf.number.suffix || ''}.`)
       }
 
@@ -1073,18 +1073,18 @@ page.prepareUploadConfig = () => {
       const key = keys[i]
 
       let value
-      if (config[key].select !== undefined) {
+      if (typeof config[key].select !== 'undefined') {
         if (form.elements[key].value !== 'default') {
           value = form.elements[key].value
         }
-      } else if (config[key].number !== undefined) {
+      } else if (typeof config[key].number !== 'undefined') {
         const parsed = parseInt(form.elements[key].value)
         if (!isNaN(parsed) && parsed !== config[key].number.default) {
           value = Math.min(Math.max(parsed, config[key].number.min), config[key].number.max)
         }
       }
 
-      if (value !== undefined) localStorage[lsKeys[key]] = value
+      if (typeof value !== 'undefined') localStorage[lsKeys[key]] = value
       else localStorage.removeItem(lsKeys[key])
     }
 
diff --git a/src/js/misc/newsfeed.js b/src/js/misc/newsfeed.js
index badbccf..bba36ff 100644
--- a/src/js/misc/newsfeed.js
+++ b/src/js/misc/newsfeed.js
@@ -15,7 +15,7 @@ newsfeed.simpleParseDate = string => {
   // Probably better to use a library if it needs to support other formats.
   const months = { Jan: 0, Feb: 1, Mar: 2, Apr: 3, May: 4, Jun: 5, Jul: 6, Aug: 7, Sep: 8, Oct: 9, Nov: 10, Dec: 11 }
   const match = string.match(/[a-zA-Z]*,\s(\d{2})\s([a-zA-Z]{3})\s(\d{4})\s(\d{2}):(\d{2}):(\d{2})\sGMT/)
-  if (match && (months[match[2]] !== undefined)) {
+  if (match && (typeof months[match[2]] !== 'undefined')) {
     const date = new Date()
     date.setUTCDate(match[1])
     date.setUTCMonth(months[match[2]])
diff --git a/src/js/misc/render.js b/src/js/misc/render.js
index fb5bc52..900d0e7 100644
--- a/src/js/misc/render.js
+++ b/src/js/misc/render.js
@@ -123,7 +123,7 @@ render.do = reload => {
   if (previousElement) previousElement.remove()
 
   const doRender = () => {
-    if (render.version === undefined) {
+    if (typeof render.version === 'undefined') {
       render.version = render.parseVersion()
     }