First thing: I searched all of the known web hosting companies for shared hosting of nodejs but I didn't find anyone. Then I came to know that nodejs cannot run on a shared host system. I want to know why?
Second thing: I am a normal guy with a normal budget. Choosing a vps or deicated server or cloud hosting makes the node run, but its out of my pocket money range as compared to the PHP shared hosting services, so should I learn node.js?
Theoretically it can, but practically it depends on hosting provider to have such infrastructure in place.
Node comparing to classic web platforms is self-sustainable platform. In case with PHP (for example), it runs on with of apache or nginx (or any other), and PHP it self is just script language with some libraries that does not do much apart of logic implementation, and requires web server solution. Web server creates socket to listen specific ports for traffic, will do its own magic and will execute PHP to process requests.
In meantime node.js creates own socket, and binds it to own port. That gives it much more low-level access, so it is web server it self. You can't bind to one port two applications, so it already unsharable.
There are services (web servers) that allow you to create proxy to route traffic to your node.js process but that is not as efficient in some cases, and shared hosting does not provide such functionality.
As node.js is still fairly young as well as is well, different, it still did not hit majority of shared hosting services. There are some available services online to host your node.js applications in a 'shared' manner.
Additionally you can rent EC2 Micro instance on AWS for free (Free Tier) for one year, which gives you plenty possibilities and time to try and test different stuff. You'll get semi-dedicated system, where you can do pretty much anything (install software, modify OS configurations, and much more), where shared hosting would not allow you to do so.
Look into Heroku. For simple low traffic apps, they are free and can easily be scaled for more traffic (for an added cost). Additionally, you use Git to deploy, so is really simple to get stuff updated...
Node doesn't work like most servers. With IIS and Apache, there is one server running multiple sites, which lends itself to shared environments. With Node, you're running your own server so instead you tend to share resources on a machine.
I can't tell you whether it's worth learning node because I don't know your motivation, but it can expand your career opportunities if you choose to go there, and to expand your skillset.
Here are a couple of hosting options in the low price range.
Other great node app hosting options include Joyent's SmartOS and Microsoft Azure. Both have a free trial period.
Azure can be a great learning platform for node.js as you can host your node app in Windows Server, Ubuntu Linux, or Azure's special "web site" shared deployment scheme.
http://www.windowsazure.com/en-us/develop/nodejs/tutorials/create-a-website-(mac)/
Another cost efective solution for node app hosting is Azure's "Web Site" approach - about $10 per month. The down side is that you have to use their shared environment that hosts your node app via IIS. In practice, this worked for well for me, but you are limited in that you can't use certain Linux functions from Node when it's running on Windows, and you won't learn how to configure the node service yourself, which may or may not be important to you. (Note: Azure's GIT deployment process works great if you want to deploy your app from a local GIT repository. Also note that NodeIIS will stop your node app when it's not in use for a certain period of time - and it auto-starts again when a request for your app comes in.)
Joyent's SmartOS platform is a Linux OS optimized for hosting your node.js app. They have impressive reliability and performance as well as great diagnostic tools.
http://wiki.joyent.com/wiki/display/jpc2/Developing+a+Node.js+Application
The most cost effective solution I have found so far is DigitalOcean, a great new hosting solution where you can host a full Linux VM for only $5/month! I have had great luck hosting Node apps there so far: https://www.digitalocean.com/pricing
a2hosting allows Node.js in shared hosting.But don't have experience there.Found from a web search
Update : Use DigitalOcean. Private VPS
来源：https://stackoverflow.com/questions/17529613/why-node-js-cant-run-on-shared-hosting