ExecJS::RuntimeUnavailable in Rails 4.1.4

UPDATE : Things are now working ! Thanks to deep, I installed node.js then got a TZInfo::DataSourceNotFound error wich got resolved by adding `gem 'tzinfo-data', platforms: [:mingw, :mswin]` and `bundle update`. Thank you sir ! First of all, I am a complete beginner on rails (just so that you get how beginner I am : I feel as being an expert for just posting here) and this is my first question here so please excuse me if I'm not very clear. So, I am a windows 7 user, learning rails with the One Month course and I encounter an error while trying to : ``` $ rake routes rake aborted! ExecJS::RuntimeUnavailable: Could not find a JavaScript runtime. See https://git hub.com/sstephenson/execjs for a list of available runtimes. c:/Users/Marc Montagne/Desktop/pinteresting/config/application.rb:7:in `<top (re quired)>' c:/Users/Marc Montagne/Desktop/pinteresting/Rakefile:4:in `<top (required)>' (See full trace by running task with --trace) ``` or ``` $ rails server c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/execjs-2.0.2/lib/execjs/run times.rb:51:in `autodetect': Could not find a JavaScript runtime. See https://gi thub.com/sstephenson/execjs for a list of available runtimes. (ExecJS::RuntimeUn available) from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/execjs-2.0.2/l ib/execjs.rb:5:in `<module:ExecJS>' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/execjs-2.0.2/l ib/execjs.rb:4:in `<top (required)>' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/uglifier-2.4.0 /lib/uglifier.rb:3:in `require' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/uglifier-2.4.0 /lib/uglifier.rb:3:in `<top (required)>' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/bundler-1.3.5/ lib/bundler/runtime.rb:72:in `require' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/bundler-1.3.5/ lib/bundler/runtime.rb:72:in `block (2 levels) in require' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/bundler-1.3.5/ lib/bundler/runtime.rb:70:in `each' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/bundler-1.3.5/ lib/bundler/runtime.rb:70:in `block in require' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/bundler-1.3.5/ lib/bundler/runtime.rb:59:in `each' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/bundler-1.3.5/ lib/bundler/runtime.rb:59:in `require' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/bundler-1.3.5/ lib/bundler.rb:132:in `require' from c:/Users/Marc Montagne/Desktop/pinteresting/config/application.rb:7 :in `<top (required)>' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/railties-4.1.4 /lib/rails/commands/commands_tasks.rb:79:in `require' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/railties-4.1.4 /lib/rails/commands/commands_tasks.rb:79:in `block in server' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/railties-4.1.4 /lib/rails/commands/commands_tasks.rb:76:in `tap' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/railties-4.1.4 /lib/rails/commands/commands_tasks.rb:76:in `server' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/railties-4.1.4 /lib/rails/commands/commands_tasks.rb:40:in `run_command!' from c:/RailsInstaller/Ruby2.0.0/lib/ruby/gems/2.0.0/gems/railties-4.1.4 /lib/rails/commands.rb:17:in `<top (required)>' from bin/rails:4:in `require' from bin/rails:4:in `<main>' ``` All that I understand is that I have a problem with ExecJS. As a total beginner I don't even know what ExecJS is. I read the great thread #12520456 and while editing runtimes.rb didn't fix my problem, it still gave me a better understanding of the situation and the willingness to solve my problem by fixing it and not "ignoring it" by adding node.js especially given the fact that I could run my server before and that I want to fix what I basically broke. What I mean by that is that I think I did something wrong when editing the PATH (I don't even know what this is) of my Windows environment for fixing an issue I had with installing Heroku. I remember editing that part as I read it somewhere and while it seemed to have fixed my Heroku issue I think it messed up the rest. Thank you in advance for your help and understanding.