cached-module-loader

Caching bundler and loader of Node.js modules which uses the cachedData feature in the vm module (available since Node.js 6).

Don't use this.

Installation

$ npm install --save cached-module-loader

Usage

Generate a cached bundle:

const { join } = require('path')
const { writeFileSync } = require('fs')
const cachedModuleLoader = require('cached-module-loader')

cachedModuleLoader.bundleDependencies('babel-core').then(bundle => {
  writeFileSync(join(__dirname, '.cached-data.bin'), cachedData)
  writeFileSync(join(__dirname, '.cached-code.js'), code)
})

Read a bundle and load the module:

const { join } = require('path')
const { readFileSync } = require('fs')
const cachedModuleLoader = require('cached-module-loader')

const cachedData = readFileSync(join(__dirname, '.cached-data.bin'))
const code = readFileSync(join(__dirname, '.cached-code.js'))

const babel = cachedModuleLoader.loadInThisContext(require.resolve('babel-core'), module, {
  moduleId: 'babel-core',
  cachedData,
  code
})

How it works

First cached-module-loader records every .js dependency of the requested module. These dependencies (and the module itself) are concatenated into one bundle. require() calls are rewritten to use absolute paths. The dependencies are wrapped in Node.js' standard module wrapper, and when loading modules, a modified require() function is passed. This function can load modules from the bundle rather than from disk.

A new vm.Script is created with the bundle as the script source, and the produceCachedData option enabled. This generates cachedData, which should be saved on the file system. Using both the source and cachedData, new vm.Script instances can be quickly created, making it much faster to load cached modules from the bundle.

Performance tests

$ node perf-tests/create-cache-data.js

$ time node perf-tests/require-with-cached-data.js
$ time node perf-tests/raw-require.js

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