@danielsan/node-lazy-loader

If you maintain a node package that has multiple functionalities that are not necessarily interdependent you are probably exporting the functionalities on your main js file like this:

module.exports = {
  feature1: require('./lib/feature1'),
  feature2: require('./lib/feature2'),
  feature3: require('./lib/feature3')
 ...
  featureN: require('./lib/featureN')
}

Some developers might install your node packages just because of a single one of those features, and most of them are loading your features like this:

const { feature1 } = require('your-package')
...

Problems

That forces their application to waste: processing time by performing the IO operations to load files from 1...N processing time by parsing those files and their respective require calls memory allocation since require will cache all loaded files

Workaround

Some developers can inspect your code and conclude that they can load the expected dependency like this:

const feature1 = require('your-package/lib/feature1')
...

That works, but not just it is a minority of the users that do that, but they can run into problems if for some reason you decide to change a file name. For example:

module.exports = {
  feature1: require('./lib/feature1-optimized'),
 ...
  featureN: require('./lib/featureN')
}

Proposed Solution

const lazy = require('@danielsan/node-lazy-loader')(module)

module.exports = {
  get feature1 () { lazy(this, 'feature1', './lib/feature1') },
  get feature2 () { lazy(this, 'feature2', './lib/feature2') },
  get feature3 () { lazy(this, 'feature3', './lib/x', 'someExportedPropertyFromX') },
 ...
  get featureN () { lazy(this, 'featureN', './lib/featureN') }
}

By using getters the request will only happen when the property is read and this very package will rewrite the getter into a property with the expected value avoiding a function call the next time it is read

For example:

// your-module index.js
const lazy = require('@danielsan/node-lazy-loader')(module)

module.exports = {
  get feature1 () {
    console.log('reading feature1')
    lazy(this, 'feature1', './lib/feature1')
  }
}

// app index.js
const yourMod = require('your-module')

// the following line when executed will print 'reading feature1' then return the value
const a = yourMod.feature1

// the following line will only return the value since it is not longer a getter but a property
const b = yourMod.feature1

Security

If you are not comfortable with passing module to a 3rd-party function you can use it as follows:

const lazyCall = require('@danielsan/node-lazy-loader')({ require: module.require })