Remove therubyracer, execjs and uglifier gems

Gemfile

@@ -47,9 +47,6 @@ gem 'sinatra', require: false
 gem 'whenever', require: false
 
 # assets
-gem 'therubyracer'
-gem 'execjs'
-gem 'uglifier'
 gem 'jquery-rails'
 gem 'jquery-ui-rails', '~> 4.2.1'
 gem 'sass-rails'

Gemfile.lock

@@ -159,13 +159,12 @@ GEM
     drb (2.2.1)
     encryptor (3.0.0)
     erubi (1.13.0)
-    execjs (2.9.1)
     factory_bot (6.4.6)
       activesupport (>= 5.0.0)
     factory_bot_rails (6.4.3)
       factory_bot (~> 6.4)
       railties (>= 5.0.0)
-    ffi (1.17.0)
+    ffi (1.17.0-x86_64-linux-gnu)
     formatador (1.1.0)
     friendly_id (5.5.1)
       activerecord (>= 4.0.0)
@@ -211,7 +210,6 @@ GEM
     launchy (3.0.1)
       addressable (~> 2.8)
       childprocess (~> 5.0)
-    libv8 (3.16.14.19.1-x86_64-linux)
     listen (3.9.0)
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
@@ -329,7 +327,6 @@ GEM
       psych (>= 4.0.0)
     recaptcha (5.17.0)
     redis (4.8.1)
-    ref (2.0.0)
     regexp_parser (2.9.2)
     reline (0.5.9)
       io-console (~> 0.5)
@@ -428,17 +425,12 @@ GEM
       climate_control
     test-unit (3.6.2)
       power_assert
-    therubyracer (0.12.3)
-      libv8 (~> 3.16.14.15)
-      ref
     thor (1.3.1)
     tilt (1.4.1)
     timecop (0.9.10)
     timeout (0.4.1)
     tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)
-    uglifier (4.2.0)
-      execjs (>= 0.3.0, < 3)
     uuidtools (2.2.0)
     vcr (6.2.0)
     webmock (3.23.1)
@@ -472,7 +464,6 @@ DEPENDENCIES
   capybara
   database_cleaner
   dotenv-rails
-  execjs
   factory_bot_rails
   friendly_id
   guard-rspec
@@ -515,9 +506,7 @@ DEPENDENCIES
   spring
   spring-commands-rspec
   test-unit
-  therubyracer
   timecop
-  uglifier
   uuidtools
   vcr
   webmock