Ruby on Rails:could not find a JavaScript runtime

[Email protected] first]# rails s

/usr/local/rvm/gems/ruby-2.0.0-p481/gems/execjs-2.2.1/lib/execjs/runtimes.rb:51: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/rvm/gems/ruby-2.0.0-p481/gems/execjs-2.2.1/lib/execjs.rb:5:in ' <module:ExecJS> '
From/usr/local/rvm/gems/ruby-2.0.0-p481/gems/execjs-2.2.1/lib/execjs.rb:4:in ' <top (required) > '
From/usr/local/rvm/gems/ruby-2.0.0-p481/gems/uglifier-1.3.0/lib/uglifier.rb:3:in ' require '
From/usr/local/rvm/gems/ruby-2.0.0-p481/gems/uglifier-1.3.0/lib/uglifier.rb:3:in ' <top (required) > '
From/usr/local/rvm/gems/[email protected]/gems/bundler-1.6.2/lib/bundler/runtime.rb:76:in ' require '
From/usr/local/rvm/gems/[email protected]/gems/bundler-1.6.2/lib/bundler/runtime.rb:76:in ' block (2 levels) in Require
From/usr/local/rvm/gems/[email protected]/gems/bundler-1.6.2/lib/bundler/runtime.rb:72:in ' Each '
From/usr/local/rvm/gems/[email protected]/gems/bundler-1.6.2/lib/bundler/runtime.rb:72:in ' block in require '
From/usr/local/rvm/gems/[email protected]/gems/bundler-1.6.2/lib/bundler/runtime.rb:61:in ' Each '
From/usr/local/rvm/gems/[email protected]/gems/bundler-1.6.2/lib/bundler/runtime.rb:61:in ' require '
From/usr/local/rvm/gems/[email protected]/gems/bundler-1.6.2/lib/bundler.rb:132:in ' require '
From/root/rails/first/config/application.rb:7:in ' <top (required) > '
From/usr/local/rvm/gems/ruby-2.0.0-p481/gems/railties-4.0.2/lib/rails/commands.rb:74:in ' require '
From/usr/local/rvm/gems/ruby-2.0.0-p481/gems/railties-4.0.2/lib/rails/commands.rb:74:in ' Block in <top ( Required) > '
From/usr/local/rvm/gems/ruby-2.0.0-p481/gems/railties-4.0.2/lib/rails/commands.rb:71:in ' Tap '
From/usr/local/rvm/gems/ruby-2.0.0-p481/gems/railties-4.0.2/lib/rails/commands.rb:71:in ' <top (required) > '
From Bin/rails:4:in ' require '
From Bin/rails:4:in ' <main> '

[email protected] first]# Yum install Nodejs

Loaded Plugins:fastestmirror, Presto
Loading mirror speeds from cached hostfile
* base:mirror.bit.edu.cn
* epel:mirrors.yun-idc.com
* extras:mirrors.yun-idc.com
* updates:mirrors.yun-idc.com
Setting up Install Process
Resolving Dependencies
--Running Transaction check
---> Package nodejs.x86_64 0:0.10.29-1.el6 'll be installed
--Finished Dependency Resolution

Dependencies resolved

=============================================================================================================== ========================
Package Arch Version Repository Size
=============================================================================================================== ========================
Installing:
Nodejs x86_64 0.10.29-1.el6 Epel 498 K

Transaction Summary
=============================================================================================================== ========================
Install 1 package (s)

Total Download size:498 k
Installed size:1.5 M
Is this OK [y/n]: Y
Downloading Packages:
Setting up and reading Presto delta metadata
Processing Delta Metadata
Package (s) data still to download:498 K
nodejs-0.10.29-1.el6.x86_64.rpm | 498 KB 00:00
Running Rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Installing:nodejs-0.10.29-1.el6.x86_64 1/1
Verifying:nodejs-0.10.29-1.el6.x86_64 1/1

Installed:
Nodejs.x86_64 0:0.10.29-1.el6

complete!

Ruby on Rails:could not find a JavaScript runtime