Ternjs plugin is not working as expected

Question

I installed ternjs_for_vim plugin but can't figure out how to use it properly. RTFM didn't help. What I get is list random JS-methods in the omni-completion. But things like completing for Node.JS modules doesn't work. For example if I type:

var fs = require('fs');
fs.

and after . there is no relevant completion (like methods readFile, readFileSync etc.)

Here is my .tern-project file:

{
    "libs": [
        "underscore",
        "jquery"
    ],
    "plugins": {
        "node": {}
    }
}

Answer 1

The documentation states (emphasis added):

In JavaScript files, the package will hook into omni completion to handle autocompletion

Omni completion doesn't automatically get triggered. It has to be manually invoked using the key sequence <C-x><C-o> in insert mode. Then you can use various keys to navigate the resulting completion menu and select the completion you want. For example, <C-y> will accept the completion and <C-e> aborts the completion leaving you with the original text.

Answer 2

Actually, there was a problem in my .vimrc config.
A long time ago I created some settings regarding Omni completion and forgot about them. So I just deleted this lines from my config:

set ofu=syntaxcomplete#Complete
autocmd FileType python set omnifunc=pythoncomplete#Complete
autocmd FileType javascript set omnifunc=javascriptcomplete#CompleteJS
autocmd FileType html set omnifunc=htmlcomplete#CompleteTags
autocmd FileType css set omnifunc=csscomplete#CompleteCSS
autocmd FileType xml set omnifunc=xmlcomplete#CompleteTags
autocmd FileType php set omnifunc=phpcomplete#CompletePHP
autocmd FileType c set omnifunc=ccomplete#Complete

and everything works like a charm now.