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drex - "dynamic require() extension". Dynamic version of Node's require() - loads fresh copy of the module every time the module file is changed.

Insanely simple, and/but astonishingly useful grab of bits, which has been brought to this world out of severe necessity.

Here is why:

  • all re-loaders I was able to find reload the whole node process, which means that the context of the process is gone;
  • but, sometimes, you don't want that! You want your process to continue running intact, at least for those clients who already deep in it, and would choke if process forgets about them;
  • sometime you have a little (or BIG) piece of code which you constantly change and, for G-d sake, do not want to sacrifice the whole your Node process for, but
  • you don't want to loose the benefits of CommonJS/require supported modularity of your code.

Here comes drex, and it comes like this:

var drex = require('drex');
... node code node code node code ...
// here goes my frea[ky/quently updated] piece of code, which lives in a js file called mucode.js: 
drex.require('./mucode.js', function(mucode)
  // at this point my mucode.js has been require()d, just like this:  
  // var mucode = require('./mucode.js'); 
  // the code of the required module is the LATEST UPDATE TO mucode.js 

Here is an example (and the reason I had to comeup with drex) from the real life when drex is irreplaceable:#

frequently updated/added event handlers:

io.sockets.on('connection', function (socket) {
  // I need to do many things here, and these things change all the time! 
  // If I use something like "forever", or "supervisor" to re-start my Node process every time  
  // when things here should change, all active sessions will be killed! 
  // Oh, no, no, no! 
  // All I want to do here, most of the time, is to put new event handler, which existing sessions  
  // do not even know about! 
  drex.require('./my_module_with_event_handlers_which_I_always_change.js', function(mymod) {
      // here I can start calling methods from my module like there is no tomorrow! 
      // and I'm guaranteed that every time I update my module, sessions which will come here after the update 
      // will get the new code, but sessions which were opened before the update will still be working with the 
      // code which existed in my module when these sessions were created. That's fair! 


drex.require(<module reference>, <callBack>);


  • <module reference> resolvable Node module reference, such as './module.js'

  • <callBack> function which is being called when the module has been require()d.

    callBack signature: callBack(module, filepath)


    • module: reference to the require()d module, and
    • filepath: full path to the module's file

Installation using NPM#

npm install drex #Even more simple installation# Just copy drex.js to the place where Node can find it, i.e. for require('./drex.js') - to the root of your Node project.


drex is watching a module for updates and cleanly re-requires the module after the update. New code is being require()d as if the new code is a totally different module, so require.cache is not a problem.