Node Express routes - Absolute URL vs Relative URL - node.js

Question

I have a simple form of this type
<form name="keywords" action="www.mydomain.com:6161/articles" method="post">
<input type="text" name="keyword" />
<input type="submit" name="submit" value="Submit" />
</form>
The Express 4 routes for handling the form post, is as follows
app.post('/articles', routes.article.keyword);
The actual route file has the following
exports.keyword = function(req,res,next){
res.send(req.body.keyword);
};
Based on the above circumstances, when I post the form in the browser, I see a page “The address wasn’t understood”.
But, if I use relative URL in the form action i.e.,
It works perfect. Why so?
Because in reality, I sometimes may have to post data to a different domain or URL altogether.

Answer 1

I will post my comment as an answer as it helped.
In order for the action to work, you need to either specify full url, that include schema:
<form name="keywords" action="http://www.example.com/articles" method="post">
Or you can just use a relative url:
<form name="keywords" action="/articles" method="post">

Answer 2

a relative path is one not starting with a / (forward-slash)... generally, this will attempt to load from the current url's base dir (you can set this in html, though the browsers default to the 'dirname' of the url (e.g. 'img/something.gif' on a page at '/some/path/index.html' will fetch it from /some/path/img/something.gif').
an absolute path is one starting with a /. it will be loaded using the same schema, host and optionally, port,user, etc (full url syntax: scheme:[//[user:password#]host[:port]][/]path[?query][#fragment]... read more here: https://en.wikipedia.org/wiki/Uniform_Resource_Locator).
a full url is one starting with a schema (http/https/ftp,etc...)... however (this comes in handy): if you're going to be using the same schema (which keeps your site's security score high), you can skip it, along with the colon.
e.g.: while viewing a site from 'https://blah.net', and attempting to load a resource from google (analytics maybe), you can reference it as:
'//google.com/path/to/whatever'
this will use https if the page was loaded over https, or http if not... keeps you from having to determine the scheme that was used when rendering the page.