rails 3.1.0 getting a javascript error?

I updated to the rails 3.1.0 from 3.0.9 and I am getting the following
error, how can I fix?

yadav@karma:$ rails g scaffold post title:string name:string message:text
/usr/local/lib/ruby/gems/1.9.1/gems/execjs-1.2.4/lib/execjs/runtimes.rb:45:in
`autodetect': Could not find a JavaScript runtime. See
https://github.com/sstephenson/execjs for a list of available
runtimes. (ExecJS::RuntimeUnavailable)
        from /usr/local/lib/ruby/gems/1.9.1/gems/execjs-1.2.4/lib/execjs.rb:5:in
`<module:ExecJS>'
        from /usr/local/lib/ruby/gems/1.9.1/gems/execjs-1.2.4/lib/execjs.rb:4:in
`<top (required)>'
        from /usr/local/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee_script.rb:1:in
`require'
        from /usr/local/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee_script.rb:1:in
`<top (required)>'
        from /usr/local/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee-script.rb:1:in
`require'

My rails environment & gems listed below

$ rails -v
Rails 3.1.0

$ ruby -v
ruby 1.9.2p290 (2011-07-09 revision 32553) [x86_64-linux]

$ gem -v
1.8.10

*** LOCAL GEMS ***

abstract (1.0.0)
actionmailer (3.1.0, 3.0.9)
actionpack (3.1.0, 3.0.9)
activemodel (3.1.0, 3.0.9)
activerecord (3.1.0, 3.0.9)
activeresource (3.1.0, 3.0.9)
activesupport (3.1.0, 3.0.9)
ansi (1.3.0)
arel (2.2.1, 2.0.10)
authlogic (3.0.3)
autotest (4.4.6)
autotest-rails-pure (4.1.2)
babosa (0.3.5)
bcrypt-ruby (3.0.0, 2.1.4)
builder (3.0.0, 2.1.2)
bundler (1.0.18, 1.0.15)
calendar_date_select (1.16.3)
cancan (1.6.5)
coffee-rails (3.1.0)
coffee-script (2.2.0)
coffee-script-source (1.1.2)
daemon_controller (0.2.6)
devise (1.4.4, 1.4.2)
diff-lcs (1.1.3, 1.1.2)
erubis (2.7.0, 2.6.6)
execjs (1.2.4)
fastri (0.3.1.1)
fastthread (1.0.7)
file-tail (1.0.6)
forgery (0.3.12)
friendly_id (3.3.0.1, 3.2.1.1)
grackle (0.1.10)
gruff (0.3.6)
hike (1.2.1)
i18n (0.6.0, 0.5.0)
jquery-rails (1.0.13)
json (1.5.4, 1.5.3)
mail (2.3.0, 2.2.19)
mechanize (2.0.1)
mime-types (1.16)
minitest (2.5.1, 1.6.0)
multi_json (1.0.3)
net-http-digest_auth (1.1.1)
net-http-persistent (2.0, 1.8)
nifty-generators (0.4.6)
nokogiri (1.5.0)
oauth (0.4.5)
orm_adapter (0.0.5)
passenger (3.0.8, 3.0.7)
patron (0.4.15, 0.4.13)
pg (0.11.0)
polyglot (0.3.2, 0.3.1)
rack (1.3.2, 1.2.3)
rack-cache (1.0.3)
rack-mount (0.8.3, 0.6.14)
rack-ssl (1.3.2)
rack-test (0.6.1, 0.5.7)
rails (3.1.0, 3.0.9)
railties (3.1.0, 3.0.9)
rake (0.9.2, 0.8.7)
rdoc (3.9.4, 3.8, 2.5.8)
RedCloth (4.2.8, 4.2.7)
rmagick (2.13.1)
rspec (2.6.0)
rspec-core (2.6.4)
rspec-expectations (2.6.0)
rspec-mocks (2.6.0)
rspec-rails (2.6.1)
ruby-json (1.1.2)
rubygems-update (1.8.10, 1.8.5)
sass (3.1.7)
sass-rails (3.1.0)
sprockets (2.0.0)
spruz (0.2.13, 0.2.11)
sqlite3 (1.3.4)
thor (0.14.6)
tilt (1.3.3)
tiny_mce (0.1.4)
tkri (0.9.5)
treetop (1.4.10, 1.4.9)
turn (0.8.2)
tzinfo (0.3.29)
uglifier (1.0.2)
w3c_validators (1.1.1)
warden (1.0.5, 1.0.4)
webrat (0.7.3)
webrobots (0.0.11, 0.0.10)
will_paginate (3.0.0, 2.3.15)
wxruby (2.0.0 x86_64-linux)
ZenTest (4.6.2, 4.6.0)

I installed coffee-script and ExecJS however I am seeing

$ rails generate scaffold Post name:string title:string content:text
/usr/local/lib/ruby/gems/1.9.1/gems/execjs-1.2.4/lib/execjs/runtimes.rb:45:in
`autodetect': Could not find a JavaScript runtime. See
https://github.com/sstephenson/execjs for a list of available
runtimes. (ExecJS::RuntimeUnavailable)
        from /usr/local/lib/ruby/gems/1.9.1/gems/execjs-1.2.4/lib/execjs.rb:5:in
`<module:ExecJS>'
        from /usr/local/lib/ruby/gems/1.9.1/gems/execjs-1.2.4/lib/execjs.rb:4:in
`<top (required)>'
        from /usr/local/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee_script.rb:1:in
`require'
        from /usr/local/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee_script.rb:1:in
`<top (required)>'
        from /usr/local/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee-script.rb:1:in
`require'
        from /usr/local/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee-script.rb:1:in
`<top (required)>'
        from /usr/local/lib/ruby/gems/1.9.1/gems/coffee-rails-3.1.0/lib/coffee-rails.rb:1:in
`require'
        from /usr/local/lib/ruby/gems/1.9.1/gems/coffee-rails-3.1.0/lib/coffee-rails.rb:1:in
`<top (required)>'
        from /usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.18/lib/bundler/runtime.rb:68:in
`require'
        from /usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.18/lib/bundler/runtime.rb:68:in
`block (2 levels) in require'
        from /usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.18/lib/bundler/runtime.rb:66:in
`each'
        from /usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.18/lib/bundler/runtime.rb:66:in
`block in require'
        from /usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.18/lib/bundler/runtime.rb:55:in
`each'
        from /usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.18/lib/bundler/runtime.rb:55:in
`require'
        from /usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.0.18/lib/bundler.rb:120:in
`require'
        from /home/yadav/dev/rails/tmp/blog/config/application.rb:7:in
`<top (required)>'
        from /usr/local/lib/ruby/gems/1.9.1/gems/railties-3.1.0/lib/rails/commands.rb:21:in
`require'
        from /usr/local/lib/ruby/gems/1.9.1/gems/railties-3.1.0/lib/rails/commands.rb:21:in
`<top (required)>'
        from script/rails:6:in `require'
        from script/rails:6:in `<main>'

try to add to Gemfile
gem 'execjs'
gem 'therubyracer'

and
bundle update
bundle install

Thanks that got things working!

Kind Regards,
Rajinder Yasdav

/usr/local/lib/ruby/gems/1.9.1/gems/execjs-2.6.0/lib/execjs/runtimes.rb:48:in
`autodetect': Could not find a JavaScript runtime. See
https://github.com/rails/execjs for a list of available runtimes.
(ExecJS::RuntimeUnavailable)
        from
/usr/local/lib/ruby/gems/1.9.1/gems/execjs-2.6.0/lib/execjs.rb:5:in
`<module:ExecJS>'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/execjs-2.6.0/lib/execjs.rb:4:in
`<top (required)>'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/coffee-script-2.4.1/lib/coffee_script.rb:1:in
`require'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/coffee-script-2.4.1/lib/coffee_script.rb:1:in
`<top (required)>'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/coffee-script-2.4.1/lib/coffee-script.rb:1:in
`require'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/coffee-script-2.4.1/lib/coffee-script.rb:1:in
`<top (required)>'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/coffee-rails-3.2.2/lib/coffee-rails.rb:1:in
`require'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/coffee-rails-3.2.2/lib/coffee-rails.rb:1:in
`<top (required)>'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.10.6/lib/bundler/runtime.rb:76:in
`require'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.10.6/lib/bundler/runtime.rb:76:in
`block (2 levels) in require'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.10.6/lib/bundler/runtime.rb:72:in
`each'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.10.6/lib/bundler/runtime.rb:72:in
`block in require'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.10.6/lib/bundler/runtime.rb:61:in
`each'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.10.6/lib/bundler/runtime.rb:61:in
`require'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/bundler-1.10.6/lib/bundler.rb:134:in
`require'
        from
/users/home101/hmurthy/projects/projects/config/application.rb:7:in
`<top (required)>'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/railties-3.2.21/lib/rails/commands.rb:53:in
`require'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/railties-3.2.21/lib/rails/commands.rb:53:in
`block in <top (required)>'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/railties-3.2.21/lib/rails/commands.rb:50:in
`tap'
        from
/usr/local/lib/ruby/gems/1.9.1/gems/railties-3.2.21/lib/rails/commands.rb:50:in
`<top (required)>'
        from script/rails:6:in `require'
        from script/rails:6:in `<main>'

Hi,

i even installed execjs and therubyracer, after that did bundle update
and install still im seeing this issue please do let me know what should
i do further???

Regards,
Harshita

Which version of ruby are you using? Use ruby -v to find out.

Post your Gemfile.lock here please.

Colin