eslint-plugin-object-imports-factory

eslint-plugin-object-imports-factory

ESLint plugin to enforce good practices using object factories to import modules.

Installation

npm install --save-dev eslint-plugin-object-imports-factory

Usage

Add object-imports-factory to the plugins section of your configuration file:

{
  "plugins": ["object-imports-factory"]
}

Then configure the rules you want to use under the rules section.

{
  "rules": {
    "object-imports-factory/require": "error",
    "object-imports-factory/import": "error"
  }
}

Rules

require

This rule enforces the usage of internal functions when using an object factory to import modules with require.

// Good
const factory = {
  foo: function () {
    return require("foo");
  },
  bar: function () {
    return require("bar");
  },
};

// Bad
const factory = {
  foo: require("foo"),
  bar: require("bar"),
};

The usage of internal functions allows to lazy load the modules, which brings massive performance improvements when the modules are not always needed. Without using this pattern, the modules will be loaded at object's creation time.

See https://github.com/tcort/link-check/pull/89/files for an example.

import

This rule enforces the usage of internal functions when using an object factory to import modules with import.

// Good
const factory = {
  foo: () => import("foo"),
  bar: () => import("bar"),
};

// Bad
const factory = {
  foo: import("foo"),
  bar: import("bar"),
};

Although the modules are lazy loaded when using import, they are resolved at the end of the current module's execution, which can be a problem if the modules are not always needed.

To reproduce this problem, consider the following example:

// index.js
const factory = {
  foo: import("foo"),
  bar: import("bar"),
};
console.log(factory);

// foo.js
console.log("foo");

// bar.js
console.log("bar");

When running node index.js, the output will be:

{ foo: Promise { <pending> }, bar: Promise { <pending> } }
foo
bar

But if you enclose them in functions:

// index.js
const factory = {
  foo: () => import("foo"),
  bar: () => import("bar"),
};
console.log(factory);

// foo.js
console.log("foo");

// bar.js
console.log("bar");

The output will be:

{ foo: [Function], bar: [Function] }