Require Extended

Extended require with awesome features!

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This package lets you modify how require should work. It adds some cool features like requiring from projects root path or redirecting all fs requires to your custom custom-fs.js module.

Installation

• npm

npm install require-extended

• yarn

yarn add require-extended

Usage

Import require extended in your entry file.

const requireExtended = require('require-extended')();

Features

Root Path

You can use require('~/file-from-root.js') at anywhere of your project.

If you want to disable this feature or change the prefix you can pass options at your entry file where you first required require-extended.

const requireExtended = require('require-extended')({
    resolveRoot: {
        enabled:true,
        prefix: '?'
    }
});

By default root path is found using the package app-root-path.

If you want to set it to a custom path you can always use setRoot. You can pass the absolute path or relative path. Relative paths will be resolved from the caller file.

const requireExtended = require('require-extended')();
requireExtended.setRoot(myCustomRootPath);

Bindings

You can return custom variables for require statements using .binding() feature. Bindings define what NodeJs should load for require.

const requireExtended = require('require-extended')();
const fsBinding = requireExtended.binding('fs', {
    readFileSync: () => {
        //custom implementation
    }
});

In this example for any file requires fs module they will receive a custom object. You can use any type of variable as a binding.

You can remove the binding by using .restore().

fsBinding.restore();

Now, all require calls to fs will receive the real fs module.

Binding matchers can be string, regex or a function that returns boolean

const requireExtended = require('require-extended')();
const jsonBinding = requireExtended.binding('./folder/language.json', {langugues: []});

All files that requires ./folder/language.json will now receive the custom json data.

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• Bindings are resolved during _load state where NodeJs checks module caches.
• Bindings are before mimics. If bindings are not matched then mimics will be working.

Mimics

Mimics are different than bindings, they change how NodeJs finds the file that should be loaded. Mimics are helping NodeJs to navigate between right files.

const requireExtended = require('require-extended')();
const fsMimic = requireExtended.mimic('fs', 'querystring');

Whenever a file requires fs module now will receive querystring module.

Mimics can be used custom files too.

const requireExtended = require('require-extended')();
const fsMimic = requireExtended.mimic('fs', './custom-fs.js');

Now the files require fs module will receieve your custom module.

Mimic paths can be used with root path resolver.

const requireExtended = require('require-extended')();
const fsMimic = requireExtended.mimic('fs', '~/custom-fs.js');

Now the files require fs module will receieve your custom module on your project root.

Mimic matchers can be string, regex or a function that returns boolean

const requireExtended = require('require-extended')();
const fsMimic = requireExtended.mimic((path) => {
    return path === 'fs'
}, '~/custom-fs.js');

Mimics can be chained

const requireExtended = require('require-extended')();
const fsMimic = requireExtended.mimic('fs', 'querystring');
const querystringMimic = requireExtended.mimic('querystring', 'http');
const http = require('fs');

Whenever a file require('fs') they will receive http module. Because fs -> querystring -> http.

You can remove mimics by using .restore().

fsMimic .restore();

Testing with require-extended

You can .binding your third-party libraries to make them return your instances.

Sinon

const requireExtended = require('require-extended')();
const sinon = require('sinon');
const fsBinding = requireExtended.binding('registerLibrary', sinon.spy());

You can return custom objects for testing. So you can easily assure that your important require lines are not removed by a coworker.