diff --git a/lib/box/index.js b/lib/box/index.js
index 50287e0e59..1fb44a5f70 100644
--- a/lib/box/index.js
+++ b/lib/box/index.js
@@ -23,7 +23,7 @@ function Box(ctx, base, options) {
     persistent: true
   }, options);
 
-  if (base.substring(base.length - 1) !== sep) {
+  if (!base.endsWith(sep)) {
     base += sep;
   }
 
@@ -158,11 +158,11 @@ Box.prototype.process = function(callback) {
 
     // Check existing files in cache
     const relativeBase = escapeBackslash(base.substring(ctx.base_dir.length));
-    const cacheFiles = Cache.filter(item => item._id.substring(0, relativeBase.length) === relativeBase).map(item => item._id.substring(relativeBase.length));
+    const cacheFiles = Cache.filter(item => item._id.startsWith(relativeBase)).map(item => item._id.substring(relativeBase.length));
 
     // Read files from directory
     return self._readDir(base, file => self._processFile(file.type, file.path)).map(file => file.path).then(files => // Handle deleted files
-      Promise.filter(cacheFiles, path => !~files.indexOf(path)).map(path => self._processFile(File.TYPE_DELETE, path)));
+      Promise.filter(cacheFiles, path => !files.includes(path)).map(path => self._processFile(File.TYPE_DELETE, path)));
   }).catch(err => {
     if (err.cause && err.cause.code !== 'ENOENT') throw err;
   }).asCallback(callback);
diff --git a/lib/extend/tag.js b/lib/extend/tag.js
index 79b59ed933..8350c8610a 100644
--- a/lib/extend/tag.js
+++ b/lib/extend/tag.js
@@ -55,21 +55,12 @@ Tag.prototype.render = function(str, options, callback) {
 
   const cache = [];
 
-  function escapeContent(str) {
-    return `<!--${placeholder}${cache.push(str) - 1}-->`;
-  }
+  const escapeContent = str => `<!--${placeholder}${cache.push(str) - 1}-->`;
 
-  const env = this.env;
+  str = str.replace(/<pre><code.*>[\s\S]*?<\/code><\/pre>/gm, escapeContent);
 
-  return new Promise((resolve, reject) => {
-    str = str.replace(/<pre><code.*>[\s\S]*?<\/code><\/pre>/gm, escapeContent);
-    env.renderString(str, options, (err, result) => {
-      if (err) return reject(err);
-      resolve(result.replace(rPlaceholder, function(...args) {
-        return cache[args[1]];
-      }));
-    });
-  });
+  return Promise.fromCallback(cb => { this.env.renderString(str, options, cb); })
+    .then(result => result.replace(rPlaceholder, (_, index) => cache[index]));
 };
 
 function NunjucksTag(name, fn) {
diff --git a/lib/hexo/load_config.js b/lib/hexo/load_config.js
index b61dc63d6c..443937e378 100644
--- a/lib/hexo/load_config.js
+++ b/lib/hexo/load_config.js
@@ -53,12 +53,12 @@ function findConfigPath(path) {
   const basename = pathFn.basename(path, extname);
 
   return fs.readdir(dirname).then(files => {
-    let item = '';
+    let item;
 
     for (let i = 0, len = files.length; i < len; i++) {
       item = files[i];
 
-      if (item.substring(0, basename.length) === basename) {
+      if (item.startsWith(basename)) {
         return pathFn.join(dirname, item);
       }
     }
diff --git a/lib/hexo/multi_config_path.js b/lib/hexo/multi_config_path.js
index db84a3588a..2886c8bfcf 100644
--- a/lib/hexo/multi_config_path.js
+++ b/lib/hexo/multi_config_path.js
@@ -17,9 +17,8 @@ module.exports = ctx => function multiConfigPath(base, configPaths, outputDir) {
   }
 
   // determine if comma or space separated
-  if (configPaths.indexOf(',') > -1) {
+  if (configPaths.includes(',')) {
     paths = configPaths.replace(' ', '').split(',');
-
   } else {
     // only one config
     let configPath = pathFn.isAbsolute(configPaths) ? configPaths : pathFn.resolve(base, configPaths);
diff --git a/lib/plugins/console/generate.js b/lib/plugins/console/generate.js
index 0407567409..a89d6833f6 100644
--- a/lib/plugins/console/generate.js
+++ b/lib/plugins/console/generate.js
@@ -123,14 +123,14 @@ function generateConsole(args = {}) {
       throw err;
     }).then(() => {
       const routeList = route.list();
-      const publicFiles = Cache.filter(item => item._id.substring(0, 7) === 'public/').map(item => item._id.substring(7));
+      const publicFiles = Cache.filter(item => item._id.startsWith('public/')).map(item => item._id.substring(7));
 
       return Promise.all([
         // Generate files
         Promise.map(routeList, generateFile),
 
         // Clean files
-        Promise.filter(publicFiles, path => !~routeList.indexOf(path)).map(deleteFile)
+        Promise.filter(publicFiles, path => !routeList.includes(path)).map(deleteFile)
       ]);
     }).spread(result => {
       const interval = prettyHrtime(process.hrtime(start));
diff --git a/lib/plugins/filter/template_locals/i18n.js b/lib/plugins/filter/template_locals/i18n.js
index 50c54b14e4..c125d2896c 100644
--- a/lib/plugins/filter/template_locals/i18n.js
+++ b/lib/plugins/filter/template_locals/i18n.js
@@ -17,7 +17,7 @@ function i18nLocalsFilter(locals) {
     const pattern = new Pattern(`${i18nDir}/*path`);
     const data = pattern.match(locals.path);
 
-    if (data && data.lang && ~i18nLanguages.indexOf(data.lang)) {
+    if (data && data.lang && i18nLanguages.includes(data.lang)) {
       lang = data.lang;
       page.canonical_path = data.path;
     } else {
diff --git a/lib/plugins/helper/css.js b/lib/plugins/helper/css.js
index 84b7fb77a7..810790c0df 100644
--- a/lib/plugins/helper/css.js
+++ b/lib/plugins/helper/css.js
@@ -12,7 +12,7 @@ function cssHelper(...args) {
     if (Array.isArray(path)) {
       result += cssHelper.apply(this, path);
     } else {
-      if (path.indexOf('?') < 0 && path.substring(path.length - 4, path.length) !== '.css') path += '.css';
+      if (!path.includes('?') && !path.endsWith('.css')) path += '.css';
       result += `<link rel="stylesheet" href="${this.url_for(path)}">`;
     }
   }
diff --git a/lib/plugins/helper/is.js b/lib/plugins/helper/is.js
index f904147441..203619d68b 100644
--- a/lib/plugins/helper/is.js
+++ b/lib/plugins/helper/is.js
@@ -1,13 +1,11 @@
 'use strict';
 
 function isCurrentHelper(path = '/', strict) {
-  const currentPath = this.path.replace(/^[^\/].*/, _ => // eslint-disable-line no-useless-escape
-    `/${_}`);
+  const currentPath = this.path.replace(/^[^/].*/, '/$&');
 
   if (strict) {
     if (path[path.length - 1] === '/') path += 'index.html';
-    path = path.replace(/^[^\/].*/, _ => // eslint-disable-line no-useless-escape
-      `/${_}`);
+    path = path.replace(/^[^/].*/, '/$&');
 
     return currentPath === path;
   }
@@ -16,10 +14,9 @@ function isCurrentHelper(path = '/', strict) {
 
   if (path === '/') return currentPath === '/index.html';
 
-  path = path.replace(/^[^\/].*/, _ => // eslint-disable-line no-useless-escape
-    `/${_}`);
+  path = path.replace(/^[^/].*/, '/$&');
 
-  return currentPath.substring(0, path.length) === path;
+  return currentPath.startsWith(path);
 }
 
 function isHomeHelper() {
diff --git a/lib/plugins/helper/js.js b/lib/plugins/helper/js.js
index 99c1a1a365..f8b561a99a 100644
--- a/lib/plugins/helper/js.js
+++ b/lib/plugins/helper/js.js
@@ -12,7 +12,7 @@ function jsHelper(...args) {
     if (Array.isArray(path)) {
       result += jsHelper.apply(this, path);
     } else {
-      if (path.indexOf('?') < 0 && path.substring(path.length - 3, path.length) !== '.js') path += '.js';
+      if (!path.includes('?') && !path.endsWith('.js')) path += '.js';
       result += `<script src="${this.url_for(path)}"></script>`;
     }
   }
diff --git a/lib/plugins/helper/list_categories.js b/lib/plugins/helper/list_categories.js
index d07c0bb1f2..f921fa1371 100644
--- a/lib/plugins/helper/list_categories.js
+++ b/lib/plugins/helper/list_categories.js
@@ -56,7 +56,7 @@ function listCategoriesHelper(categories, options) {
 
         // special case: category page
         if (!isCurrent && self.page.base) {
-          if (self.page.base.indexOf(cat.path) === 0) {
+          if (self.page.base.startsWith(cat.path)) {
             isCurrent = true;
           }
         }
diff --git a/lib/plugins/helper/tagcloud.js b/lib/plugins/helper/tagcloud.js
index c3e34b8d83..e7796bd9f1 100644
--- a/lib/plugins/helper/tagcloud.js
+++ b/lib/plugins/helper/tagcloud.js
@@ -204,7 +204,7 @@ function tagcloudHelper(tags, options) {
 
   tags.sort('length').forEach(tag => {
     const length = tag.length;
-    if (~sizes.indexOf(length)) return;
+    if (sizes.includes(length)) return;
 
     sizes.push(length);
   });
diff --git a/lib/plugins/helper/url_for.js b/lib/plugins/helper/url_for.js
index d9a6863569..964ea49617 100644
--- a/lib/plugins/helper/url_for.js
+++ b/lib/plugins/helper/url_for.js
@@ -4,7 +4,7 @@ const url = require('url');
 const _ = require('lodash');
 
 function urlForHelper(path = '/', options) {
-  if (path[0] === '#' || path.substring(0, 2) === '//') {
+  if (path[0] === '#' || path.startsWith('//')) {
     return path;
   }
 
diff --git a/lib/plugins/tag/img.js b/lib/plugins/tag/img.js
index 50810e0822..b26c275374 100644
--- a/lib/plugins/tag/img.js
+++ b/lib/plugins/tag/img.js
@@ -17,7 +17,7 @@ module.exports = ctx => {
   const config = ctx.config;
 
   function makeUrl(path) {
-    if (path[0] === '#' || path.substring(0, 2) === '//') {
+    if (path[0] === '#' || path.startsWith('//')) {
       return path;
     }
 
diff --git a/lib/theme/processors/source.js b/lib/theme/processors/source.js
index b0130a228e..c291d19413 100644
--- a/lib/theme/processors/source.js
+++ b/lib/theme/processors/source.js
@@ -29,7 +29,7 @@ exports.pattern = new Pattern(path => {
   if (!_.startsWith(path, 'source/')) return false;
 
   path = path.substring(7);
-  if (common.isHiddenFile(path) || common.isTmpFile(path) || ~path.indexOf('node_modules')) return false;
+  if (common.isHiddenFile(path) || common.isTmpFile(path) || path.includes('node_modules')) return false;
 
   return {path};
 });