uncache

Like require(), but do not put the required package into the cache to facilitate live coding (actually, it removes the required module from the cache!).

What Can You Do?

• Create a web server that you don't have to restart when you change the code.

Usage

var live = require('uncache')(require)

Now, use live('module') instead of require('module'). It will load the file each time.

When the module exports a function

var func = live.function('./module')

When func() is called, it will reload the module before calling it. Of course, this assumes that the module exports a function.

Use Cases

Restartless Express Application

One annoying thing when creating web applications with Node.js is that you have to restart the server when you change the code.

Even with nodemon that restarts the server automatically, it's still annoying.

Since the app returned by express() is a function that can be passed to http.createServer, you can create a web server like this:

var live = require('uncache')(require)
var http = require('http')
 
http.createServer(live.function('./app'))
    .listen(3002, '127.0.0.1')

And app.js like this:

var express = require('express')
var app = module.exports = express()
 
app.get('/', function(req, res, next) {
  res.send('hello')
})

Each time you send a request to this server, a new application is created.

That means when you change the code, for example, from 'hello' to 'world', and then refresh the page.

Going live: when you want to go production, just change live.function to require, and it's done!

What It Does Not Do

This module is only concerned about making require() clear the cache.

It does not have these features:

Switching between live and require.

Create your own abstraction, such as:

function load(module) {
  return (process.env.NODE_ENV == 'production') ? require(module) : live(module)
}

Do some cleanup when a module is reloaded.

Maybe you can use a global variable for this. Here is a cleanup function:

function cleanup(module, fn) {
 
  var key = 'cleanup:' + module.id
 
  // If there is a cleanup function for this module,
  // this means the module is loaded, so, call it:
  if (global[key]) {
    global[key]()
  }
 
  // Register the cleanup function.
  global[key] = fn
 
}

When cleanup is called the second time (when the module is reloaded), it will detect the cleanup function from the first load and run it.

console.log('Start up!')
 
cleanup(module, function() {
  console.log('Shut down!')
})