diff --git a/.rubocop.yml b/.rubocop.yml
index 262358bdc..9eb10ab14 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -4,3 +4,5 @@ Metrics/MethodLength:
   Max: 16
 Style/BracesAroundHashParameters:
   EnforcedStyle: context_dependent
+Style/RegexpLiteral:
+  EnforcedStyle: slashes
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 980daafd9..1823ac370 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 - Fix rake task fablab:es_build_projects_index for ElasticSearch > 1.7
 - Fix Dockerfile: yarn was not setup correctly
+- Updated Uglifier gem to support ES6 syntax
 
 # v2.7.2 2018 November 29
 
diff --git a/Gemfile b/Gemfile
index af491f407..07dce838d 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,7 +7,7 @@ gem 'rails', '4.2.10'
 gem 'sass-rails', '5.0.1'
 
 # Use Uglifier as compressor for JavaScript assets
-gem 'uglifier', '>= 1.3.0'
+gem 'uglifier', '>= 4.1.20'
 # See https://github.com/sstephenson/execjs#readme for more supported runtimes
 gem 'therubyracer', '= 0.12.0', platforms: :ruby
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 8ff2a8124..5539afb1a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -460,9 +460,8 @@ GEM
       tzinfo
     tzinfo (1.2.4)
       thread_safe (~> 0.1)
-    uglifier (2.7.1)
-      execjs (>= 0.3.0)
-      json (>= 1.8.0)
+    uglifier (4.1.20)
+      execjs (>= 0.3.0, < 3)
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.6)
@@ -564,7 +563,7 @@ DEPENDENCIES
   therubyracer (= 0.12.0)
   twitter
   twitter-text
-  uglifier (>= 1.3.0)
+  uglifier (>= 4.1.20)
   unicorn
   vcr
   web-console (~> 2.1.3)
diff --git a/config/environments/production.rb b/config/environments/production.rb
index 238ebcfd1..50161662a 100644
--- a/config/environments/production.rb
+++ b/config/environments/production.rb
@@ -22,10 +22,8 @@ Rails.application.configure do
   # Disable Rails's static asset server (Apache or nginx will already do this).
   config.serve_static_files = false
 
-  # Compress JavaScripts and CSS.
-  config.assets.js_compressor = :uglifier
-  # if you want disable variable name mangling
-  config.assets.js_compressor = Uglifier.new(mangle: false)
+  # Compress JavaScripts and CSS. We disable variable name mangling and enable ES6 support
+  config.assets.js_compressor = Uglifier.new(mangle: false, harmony: true)
 
   # config.assets.css_compressor = :sass
 
diff --git a/config/routes.rb b/config/routes.rb
index 0b4596592..9816030d7 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -113,7 +113,7 @@ Rails.application.routes.draw do
     resources :event_themes
     resources :age_ranges
     resources :statistics, only: [:index]
-    resources :custom_assets, only: [:show, :create, :update]
+    resources :custom_assets, only: %i[show create update]
     resources :tags
     resources :stylesheets, only: [:show]
     resources :auth_providers do
@@ -122,14 +122,15 @@ Rails.application.routes.draw do
       post 'send_code', action: 'send_code', on: :collection
     end
     resources :abuses, only: [:create]
-    resources :open_api_clients, only: [:index, :create, :update, :destroy] do
+    resources :open_api_clients, only: %i[index create update destroy] do
       patch :reset_token, on: :member
     end
     resources :price_categories
     resources :spaces
 
     # i18n
-    get 'translations/:locale/:state' => 'translations#show', :constraints => { :state => /[^\/]+/ } # allow dots in URL for 'state'
+    # regex allows using dots in URL for 'state'
+    get 'translations/:locale/:state' => 'translations#show', :constraints => { state: /[^\/]+/ }
 
     # XLSX exports
     get 'exports/:id/download' => 'exports#download'
@@ -166,12 +167,12 @@ Rails.application.routes.draw do
     end
   end
 
-  %w(account event machine project subscription training user space).each do |path|
+  %w[account event machine project subscription training user space].each do |path|
     post "/stats/#{path}/_search", to: "api/statistics##{path}"
     post "/stats/#{path}/export", to: "api/statistics#export_#{path}"
   end
-  post '/stats/global/export', to: "api/statistics#export_global"
-  post '_search/scroll', to: "api/statistics#scroll"
+  post '/stats/global/export', to: 'api/statistics#export_global'
+  post '_search/scroll', to: 'api/statistics#scroll'
 
   match '/project_collaborator/:valid_token', to: 'api/projects#collaborator_valid', via: :get