lazy-cache

What is lazy-cache?

The lazy-cache npm package is designed to lazily require modules, meaning that the modules are only required when they are actually needed. This can help improve the performance of your application by deferring the loading of modules until they are used.

What are lazy-cache's main functionalities?

Lazy Loading of Modules

This feature allows you to defer the loading of a module until it is actually used in your code. In the example, the 'fs' module is not loaded until the 'readFileSync' method is called.

const lazy = require('lazy-cache')(require);
const fs = lazy('fs');

// fs is not loaded until it is used
fs.readFileSync('path/to/file.txt', 'utf8');

Custom Lazy Loading

You can also use lazy-cache to lazily load your own custom modules. In this example, the './customModule' is not loaded until 'someFunction' is called.

const lazy = require('lazy-cache')(require);
const customModule = lazy('./customModule');

// customModule is not loaded until it is used
customModule.someFunction();

Other packages similar to lazy-cache

require-lazy

The require-lazy package provides similar functionality by allowing you to lazily require modules. It offers a simple API for deferring the loading of modules until they are needed, similar to lazy-cache.

proxyquire

Proxyquire is a powerful tool for mocking dependencies during testing, but it also supports lazy loading of modules. It allows you to mock out dependencies and control when they are loaded, providing more flexibility compared to lazy-cache.

import-lazy

Import-lazy is another package that allows you to lazily import modules. It uses ES6 proxies to defer the loading of modules until they are accessed, offering a modern alternative to lazy-cache.

README

lazy-cache

Cache requires to be lazy-loaded when needed.

Install

Install with npm:

$ npm install lazy-cache --save

webpack users

If you use webpack and are experiencing issues, try using unlazy-loader, a webpack loader that fixes the webpack bug that prevents webpack from working with native javascript getters.

Usage

var utils = require('lazy-cache')(require);

Use as a property on lazy

The module is also added as a property to the lazy function so it can be called without having to call a function first.

var utils = require('lazy-cache')(require);

// `npm install glob`
utils('glob');

// glob sync
console.log(utils.glob.sync('*.js'));

// glob async
utils.glob('*.js', function (err, files) {
  console.log(files);
});

Use as a function

var utils = require('lazy-cache')(require);
var glob = utils('glob');

// `glob` is a now a function that may be called when needed
glob().sync('foo/*.js');

Aliases

An alias may be passed as the second argument if you don't want to use the automatically camel-cased variable name.

Example

var utils = require('lazy-cache')(require);

// alias `ansi-yellow` as `yellow`
utils('ansi-yellow', 'yellow');
console.log(utils.yellow('foo'));

Dot notation may also be used in the alias to create an object hierarchy.

Example

var utils = require('lazy-cache')(require);
utils('ansi-cyan', 'color.cyan');
utils('ansi-yellow', 'color.yellow');
utils('ansi-magenta', 'color.magenta');
console.log(utils.color.cyan('foo'));
console.log(utils.color.yellow('bar'));
console.log(utils.color.magenta('baz'));

Browserify usage

Example

var utils = require('lazy-cache')(require);
// temporarily re-assign `require` to trick browserify
var fn = require;
require = utils;
// list module dependencies (here, `require` is actually `lazy-cache`)
require('glob');
require = fn; // restore the native `require` function

/**
 * Now you can use glob with the `utils.glob` variable
 */

// sync
console.log(utils.glob.sync('*.js'));

// async
utils.glob('*.js', function (err, files) {
  console.log(files.join('\n'));
});

Kill switch

In certain rare edge cases it may be necessary to unlazy all lazy-cached dependencies (5 reported cases after ~30 million downloads).

To force lazy-cache to immediately invoke all dependencies, do:

process.env.UNLAZY = true;

Related projects

You might also be interested in these projects:

lint-deps: CLI tool that tells you when dependencies are missing from package.json and offers you a… more | homepage

Contributing

Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.

Building docs

Generate readme and API documentation with verb:

$ npm install verb && npm run docs

Or, if verb is installed globally:

$ verb

Running tests

Install dev dependencies:

$ npm install -d && npm test

Author

Jon Schlinkert

• github/jonschlinkert
• twitter/jonschlinkert

License

Copyright © 2016, Jon Schlinkert. Released under the MIT license.

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This file was generated by verb, v0.9.0, on April 28, 2016.