barrelsby

Automatically create TypeScript barrels for your entire code base.

About Barrels

Barrels are files that rollup exports from several modules into a single convenient module typically named index.ts. They tend to help simplify large blocks of import statements at the top of files and help to group up related functionality.

A barrel file looks like this:

export * from "./DropDown";
export * from "./TextBox";
export * from "./CheckBox";
export * from "./DateTimePicker";
export * from "./Slider";

It can help you go from messy imports like this:

import {DropDown} from "./src/controls/DropDown";
import {TextBox} from "./src/controls/TextBox";
import {CheckBox} from "./src/controls/CheckBox";
import {DateTimePicker} from "./src/controls/DateTimePicker";
import {Slider} from "./src/controls/Slider";

...to something tidier like this:

import {DropDown, TextBox, CheckBox, DateTimePicker, Slider} from "./src/controls";

...or even this:

import * as Controls from "./src/controls/index";

More Reading

• Angular Glossary
• TattooCoder Blog

Usage

To install Barrelsby:

npm install --save-dev barrelsby

To run barrelsby first add a script to the package.json file:

{
  "scripts": [
    "generate-barrels": "barrelsby --delete"
  ]
}

You can now generate barrels:

npm run generate-barrels

Configuration Options

Barrelsby accepts a number of options to help refine how your barrels are created. These options can be configured from the command line or using a configuration file.

-c [path] or --config [path]

Specifies the location of the barrelsby configuration file. This file must be a .json file. You can include any of the configuration options using their long name.

-d [path] or --directory [path]

Specifies the root directory where barrels will be created from. Uses the current directory by default.

-D or --delete

Deletes any existing barrels encountered by barrelsby. Disabled by default.

-e [regex...] or --exclude [regex...]

Excludes any files whose paths match any of the specified regular expressions.

-H or --help

Displays help information on the command line arguments that barrelsby accepts.

-i [regex...] or --include [regex...]

Only include files whose paths match any of the specified regular expressions.

-l [mode] or --location [mode]

The mode that barrelsby should use to determine where which directories to create barrels in. Defaulted to top.

• top only creates a barrel in the target directory.
• below creates a barrel in every directory just below the target directory.
• all creates a barrel in every directory below (and including) the target directory.
• replace only creates barrels in directories where one already existed.
• branch creates a barrel in every directory that contains other directories.

-n [name] or --name [name]

Specifies the name to use for creating new barrels (and identifying old ones). .ts wil be appended if not included in the name. Barrels names will be defaulted to index.ts.

-s [mode] or --structure [mode]

The structure that barrelsby should create inside the barrels. Defaulted to flat.

flat

Exports modules without any nesting.

export * from "./barrel";
export * from "./index";
export * from "./directory2/script";
export * from "./directory2/directory4/deeplyNested";
export * from "./directory3/program";

filesystem

Exports modules as a nested structure that matches the file system directories.

import * as barrelts from "./barrel";
import * as directory2directory4deeplyNestedts from "./directory2/directory4/deeplyNested";
import * as directory2scriptts from "./directory2/script";
import * as directory3programts from "./directory3/program";
import * as indexts from "./index";
export {barrelts as barrel};
export const directory2 = {
  directory4: {
    deeplyNested: directory2directory4deeplyNestedts,
  },
  script: directory2scriptts,
};
export const directory3 = {
  program: directory3programts,
};
export {indexts as index};

-q or --singleQuotes

Use 'single quotes' in the generated barrel files instead of the default "double quotes".

-v or --version

Display the barrelsby version number.

-V or --verbose

Display additional debug information.

Requirements

Requires node v6.0.0 or greater for ES6 syntax.

Contributing

If you are interested in contributing to barrelsby there are plenty of tagged issues that can be picked up, or feel free to suggest your own feature in an issue.

Most coding conventions are enforced by TSLint but in general:

• Use small functions instead of classes.
• Avoid abreviated identifiers.
• Write short simple test.