title: Is 'require(...)' a common javascript pattern or a library function?
body: <p>I usually find this as the first line in node.js scripts/modules as well as phantomJS, casperJS etc. I'm curious, if this is a common pattern for server-side javascript (SSJS) (similar to <code>#include</code> in C/C++ or <code>import</code> in Java) or is it a a library like RequireJS or LabJS that is being called for this inclusion (neither of which I have gotten a chance to use in practice, as yet)?</p>
  
  <p>e.g. <code>var http = require('http')</code> or <code>var casper = require('casper').create()</code></p>
  
  <p>I'm curious if this is a pattern that has become <em>standardized</em> for SSJS or does every library/tool call an existing function?</p>
  
  <p>Please pardon the <em>n00b</em> dimension to the question but I would like to know the 'why' behind its omnipresence :)</p>