Lazy loading of Node.js modules

Usage no npm install needed!

<script type="module">
  import lazyModules from '';


lazy-modules Build Status

lazy-modules implements an easy way to bulk lazy-load Node.js/io.js modules, perfect for implementing in a build system with many imports such as gulp or grunt.


v8's Script::Compile, called when require() is used, usually takes a relatively long time. Multiply this by the 20 packages your Gulpfile.js imports, times the 10 each of those imports, times 5... you get the point. Just running a linter forces v8 to compile everything, sometimes taking ~5 seconds or worse. If you're impatient like me, this is perfect for you.

This is the time it takes to load and not use vs lazy-load gulpjs/gulp-util:

> var lazy = require('lazy-modules');
> console.time('lazy-load'); lazy('node_modules/gulp-util'); console.timeEnd('lazy-load');
lazy-load: 6ms
> console.time('load'); gulp_util; console.timeEnd('load');
load: 787ms

If you don't actually use gulp_util in your Gulpfile, it'll take 6ms to lazy load it. If you do use it, it'll take 787ms to load it - a massive decrease especially when you your task might only take ~100ms.


$ npm i lazy-modules --save


There are three modules in the example directory: a.js, b.js, c.js. In this example, we'll lazy load them all but only actually run two of them:

var lazy = require('lazy-modules');

// we now have access to a, b, and c
console.log(a == 1, b == 2);

// we didn't use c, so it was never loaded

In the same way, it can be used with Gulp packages like so:

var lazy = require('lazy-modules');

// if a module has a dash, it is changed to an underscore
gulp_util.log('gulp-util was lazily loaded!');



  • glob: either a String or Array

When a string is passed, all modules will be lazy-loaded that match the given glob. If glob is an Array, they will be mapped over the lazy function individually.


MIT license