diff --git a/layout/_partials/head/head-unique.swig b/layout/_partials/head/head-unique.swig
index 2d831655d0..d31f460afb 100644
--- a/layout/_partials/head/head-unique.swig
+++ b/layout/_partials/head/head-unique.swig
@@ -10,7 +10,7 @@
 <script id="page-configurations">
   // https://hexo.io/docs/variables.html
   CONFIG.page = {
-    sidebar: {{ page.sidebar | json_encode }},
+    sidebar: {{ page.sidebar | json }},
     isHome: {{ is_home() }},
     isPost: {{ is_post() }},
     isPage: {{ is_page() }},
diff --git a/layout/_partials/head/head.swig b/layout/_partials/head/head.swig
index 2e27de8493..ec90853d90 100644
--- a/layout/_partials/head/head.swig
+++ b/layout/_partials/head/head.swig
@@ -78,10 +78,10 @@
     scheme: '{{ theme.scheme }}',
     version: '{{ version }}',
     exturl: {{ theme.exturl }},
-    sidebar: {{ theme.sidebar | json_encode }},
-    copycode: {{ theme.codeblock.copy_button | json_encode }},
-    back2top: {{ theme.back2top | json_encode }},
-    bookmark: {{ theme.bookmark | json_encode }},
+    sidebar: {{ theme.sidebar | json }},
+    copycode: {{ theme.codeblock.copy_button | json }},
+    back2top: {{ theme.back2top | json }},
+    bookmark: {{ theme.bookmark | json }},
     fancybox: {{ theme.fancybox }},
     mediumzoom: {{ theme.mediumzoom }},
     lazyload: {{ theme.lazyload }},
@@ -90,12 +90,12 @@
       appID: '{{ config.algolia.applicationID }}',
       apiKey: '{{ config.algolia.apiKey }}',
       indexName: '{{ config.algolia.indexName }}',
-      hits: {{ theme.algolia_search.hits | json_encode }},
-      labels: {{ theme.algolia_search.labels | json_encode }}
+      hits: {{ theme.algolia_search.hits | json }},
+      labels: {{ theme.algolia_search.labels | json }}
     },
-    localsearch: {{ theme.local_search | json_encode }},
+    localsearch: {{ theme.local_search | json }},
     path: '{{ config.search.path }}',
-    motion: {{ theme.motion | json_encode }},
+    motion: {{ theme.motion | json }},
     translation: {
       copy_button: '{{ __("post.copy_button") }}',
       copy_success: '{{ __("post.copy_success") }}',
diff --git a/layout/_scripts/pages/schedule.swig b/layout/_scripts/pages/schedule.swig
index 0898cd966a..068a43f08a 100644
--- a/layout/_scripts/pages/schedule.swig
+++ b/layout/_scripts/pages/schedule.swig
@@ -12,7 +12,7 @@
   }
 
   // Read config form theme config file
-  Object.assign(calendar, {{ theme.calendar | json_encode }});
+  Object.assign(calendar, {{ theme.calendar | json }});
 
   var now = new Date();
   var timeMax = new Date();
diff --git a/layout/_third-party/comments/valine.swig b/layout/_third-party/comments/valine.swig
index 7c5713bcb5..bec434bd10 100644
--- a/layout/_third-party/comments/valine.swig
+++ b/layout/_third-party/comments/valine.swig
@@ -13,7 +13,7 @@ NexT.utils.getScript('{{ valine_uri }}', () => {
     notify: {{ theme.valine.notify }},
     appId: '{{ theme.valine.appid }}',
     appKey: '{{ theme.valine.appkey }}',
-    placeholder: '{{ theme.valine.placeholder | escape }}',
+    placeholder: {{ theme.valine.placeholder | json }},
     avatar: '{{ theme.valine.avatar }}',
     meta: guest,
     pageSize: '{{ theme.valine.pageSize }}' || 10,
diff --git a/scripts/events/lib/config.js b/scripts/events/lib/config.js
index 0f474516fa..d02120ac71 100644
--- a/scripts/events/lib/config.js
+++ b/scripts/events/lib/config.js
@@ -24,11 +24,9 @@ module.exports = hexo => {
     merge(hexo.theme.config, hexo.config.theme_config);
   }
 
-  if (hexo.theme.config.cache && hexo.theme.config.cache.enable) {
-    if (hexo.config.relative_link) {
-      hexo.log.warn('Since caching is turned on, the `relative_link` option in Hexo `_config.yml` is set to `false` to avoid potential hazards.');
-      hexo.config.relative_link = false;
-    }
+  if (hexo.theme.config.cache && hexo.theme.config.cache.enable && hexo.config.relative_link) {
+    hexo.log.warn('Since caching is turned on, the `relative_link` option in Hexo `_config.yml` is set to `false` to avoid potential hazards.');
+    hexo.config.relative_link = false;
   }
 
   // Custom languages support. Introduced in NexT v6.3.0.
diff --git a/scripts/events/lib/injects.js b/scripts/events/lib/injects.js
index d546b921e9..6835ad09d1 100644
--- a/scripts/events/lib/injects.js
+++ b/scripts/events/lib/injects.js
@@ -47,7 +47,7 @@ module.exports = hexo => {
 
   // Inject stylus, and get absolute path base on hexo dir.
   points.styles.forEach(type => {
-    hexo.theme.config.injects[type] = injects[type].files.map((item) => path.resolve(hexo.base_dir, item));
+    hexo.theme.config.injects[type] = injects[type].files.map(item => path.resolve(hexo.base_dir, item));
   });
 
   // Inject views
diff --git a/scripts/helpers/font.js b/scripts/helpers/font.js
index 213bd280ae..a381adaa1a 100644
--- a/scripts/helpers/font.js
+++ b/scripts/helpers/font.js
@@ -3,27 +3,27 @@
 'use strict';
 
 hexo.extend.helper.register('next_font', () => {
-  var fontConfig = hexo.theme.config.font;
+  var config = hexo.theme.config.font;
 
-  if (!fontConfig || !fontConfig.enable) {
+  if (!config || !config.enable) {
     return '';
   }
 
   var fontDisplay = '&display=swap';
   var fontSubset = '&subset=latin,latin-ext';
   var fontStyles = ':300,300italic,400,400italic,700,700italic';
-  var fontHost = fontConfig.host || '//fonts.googleapis.com';
+  var fontHost = config.host || '//fonts.googleapis.com';
 
-  //Get a font list from fontConfig
+  //Get a font list from config
   var fontFamilies = ['global', 'title', 'headings', 'posts', 'codes'].map(item => {
-    if (fontConfig[item] && fontConfig[item].family && fontConfig[item].external) {
-      return fontConfig[item].family + fontStyles;
+    if (config[item] && config[item].family && config[item].external) {
+      return config[item].family + fontStyles;
     }
     return '';
   });
 
   fontFamilies = fontFamilies.filter(item => item !== '');
-  fontFamilies = Array.from(new Set(fontFamilies));
+  fontFamilies = [...new Set(fontFamilies)];
   fontFamilies = fontFamilies.join('|');
 
   // Merge extra parameters to the final processed font string
diff --git a/scripts/helpers/next-url.js b/scripts/helpers/next-url.js
index 0be848d890..95d6faca3f 100644
--- a/scripts/helpers/next-url.js
+++ b/scripts/helpers/next-url.js
@@ -6,10 +6,11 @@
 
 'use strict';
 
+const { htmlTag } = require('hexo-util');
+const url = require('url');
+
 hexo.extend.helper.register('next_url', function(path, text, options) {
-  var htmlTag = require('hexo-util').htmlTag;
   var config = this.config;
-  var url = require('url');
   var data = url.parse(path);
   var siteHost = url.parse(config.url).hostname || config.url;
 
diff --git a/scripts/tags/include-raw.js b/scripts/tags/include-raw.js
index 2ef3c4a1f3..c4440fc155 100644
--- a/scripts/tags/include-raw.js
+++ b/scripts/tags/include-raw.js
@@ -6,18 +6,18 @@
 
 'use strict';
 
-var pathFn = require('path');
-var fs = require('hexo-fs');
+const path = require('path');
+const fs = require('hexo-fs');
 
 function includeRaw(args) {
-  var path = pathFn.join(hexo.source_dir, args[0]);
+  var file = path.join(hexo.source_dir, args[0]);
 
-  return fs.exists(path).then(exist => {
+  return fs.exists(file).then(exist => {
     if (!exist) {
       hexo.log.error('Include file not found!');
       return;
     }
-    return fs.readFile(path).then(contents => {
+    return fs.readFile(file).then(contents => {
       if (!contents) {
         hexo.log.warn('Include file empty.');
         return;
diff --git a/source/css/_variables/base.styl b/source/css/_variables/base.styl
index 915a825147..82c8081b65 100644
--- a/source/css/_variables/base.styl
+++ b/source/css/_variables/base.styl
@@ -84,8 +84,7 @@ $font-weight-bolder       = 700;
 
 
 // Font size
-$font-size-base           = 1em;
-$font-size-base           = unit(hexo-config('font.global.size'), em) if hexo-config('font.enable') and hexo-config('font.global.size') is a 'unit';
+$font-size-base           = (hexo-config('font.enable') and hexo-config('font.global.size') is a 'unit') ? unit(hexo-config('font.global.size'), em) : 1em;
 $font-size-smallest       = .75em;
 $font-size-smaller        = .8125em;
 $font-size-small          = .875em;
@@ -97,8 +96,7 @@ $font-size-largest        = 1.375em;
 
 // Headings font size
 $font-size-headings-step  = .125em;
-$font-size-headings-base  = 1.625em;
-$font-size-headings-base  = unit(hexo-config('font.headings.size'), em) if hexo-config('font.enable') and hexo-config('font.headings.size') is a 'unit';
+$font-size-headings-base  = (hexo-config('font.enable') and hexo-config('font.headings.size') is a 'unit') ? unit(hexo-config('font.headings.size'), em) : 1.625em;
 
 
 // Global line height
@@ -198,8 +196,7 @@ $brand-color                    = white;
 $brand-hover-color              = white;
 $brand-bg                       = $black-deep;
 
-$font-size-title                = $font-size-largest;
-$font-size-title                = unit(hexo-config('font.title.size'), em) if hexo-config('font.enable') and hexo-config('font.title.size') is a 'unit';
+$font-size-title                = (hexo-config('font.enable') and hexo-config('font.title.size') is a 'unit') ? unit(hexo-config('font.title.size'), em) : $font-size-largest;
 $font-size-subtitle             = $font-size-smaller;
 $subtitle-color                 = $grey-dark;
 $site-subtitle-color            = $grey-dark;
@@ -215,7 +212,7 @@ $posts-collapse-margin-mobile   = 20px;
 // Variables for sidebar section elements.
 // --------------------------------------------------
 
-$sidebar-offset                       = unit(hexo-config('sidebar.offset'), px) if hexo-config('sidebar.offset') is a 'unit';
+$sidebar-offset                       = hexo-config('sidebar.offset') is a 'unit' ? unit(hexo-config('sidebar.offset'), px) : 12px;
 $sidebar-nav-color                    = $black-light;
 $sidebar-nav-hover-color              = $whitesmoke;
 $sidebar-highlight                    = $blue-bright;
@@ -284,7 +281,7 @@ $center-quote-right           = '../images/quote-r.svg';
 // Note colors
 // --------------------------------------------------
 // Read note light_bg_offset from NexT config and set in "$lbg%" to use it as string variable.
-hexo-config('note.light_bg_offset') is a 'unit' ? ($lbg = unit(hexo-config('note.light_bg_offset'), "%")) : ($lbg = 0);
+$lbg = hexo-config('note.light_bg_offset') is a 'unit' ? unit(hexo-config('note.light_bg_offset'), "%") : 0;
 
 // Default
 $note-default-border        = #777;