Mastering `eslint-plugin-typescript-sort-keys`: A Comprehensive Guide

In the world of TypeScript development, maintaining a clean and organized codebase is crucial. One aspect of code organization is the proper sorting of keys in objects and types. The eslint-plugin-typescript-sort-keys is a powerful ESLint plugin that helps developers enforce a consistent sorting order for keys in TypeScript code. This blog post will delve into the fundamental concepts of eslint-plugin-typescript-sort-keys, explain its usage methods, share common practices, and outline best practices to help you make the most of this plugin.

Table of Contents

  1. Fundamental Concepts
  2. Installation and Setup
  3. Usage Methods
  4. Common Practices
  5. Best Practices
  6. Conclusion
  7. References

Fundamental Concepts

What is eslint-plugin-typescript-sort-keys?

eslint-plugin-typescript-sort-keys is an ESLint plugin specifically designed for TypeScript projects. It adds a rule to ESLint that checks the sorting order of keys in object literals and type definitions. By enforcing a consistent sorting order, it makes the code more readable and maintainable.

Why Sort Keys?

Sorting keys in objects and types has several benefits:

  • Readability: Sorted keys make it easier to find specific properties in an object or type.
  • Consistency: It enforces a standard across the codebase, making the code more predictable.
  • Diffing: When reviewing code changes, sorted keys make it easier to spot differences between versions.

Installation and Setup

Installation

To install eslint-plugin-typescript-sort-keys, you can use npm or yarn:

npm install --save-dev eslint-plugin-typescript-sort-keys
# or
yarn add --dev eslint-plugin-typescript-sort-keys

Setup

After installation, you need to configure ESLint to use the plugin. Open your .eslintrc file and add the following:

{
  "plugins": ["typescript-sort-keys"],
  "rules": {
    "typescript-sort-keys/interface": "error",
    "typescript-sort-keys/type-literal": "error"
  }
}

This configuration enables the sorting rules for interfaces and type literals.

Usage Methods

Basic Usage

Once the plugin is set up, ESLint will start checking the sorting order of keys in your TypeScript code. For example, consider the following type definition:

type Person = {
  age: number;
  name: string;
  id: number;
};

With the typescript-sort-keys plugin enabled, ESLint will report an error because the keys are not sorted alphabetically. The correct version would be:

type Person = {
  age: number;
  id: number;
  name: string;
};

Configuration Options

The plugin provides several configuration options to customize the sorting behavior. For example, you can sort keys in descending order:

{
  "rules": {
    "typescript-sort-keys/interface": ["error", "desc"],
    "typescript-sort-keys/type-literal": ["error", "desc"]
  }
}

Now, the keys will be sorted in descending alphabetical order.

Common Practices

Sorting Object Literals

When defining object literals, make sure to sort the keys according to the configured order. For example:

const person = {
  age: 30,
  id: 123,
  name: "John Doe"
};

Handling Complex Types

For more complex types, such as nested objects or arrays of objects, apply the sorting rule recursively. For example:

type Company = {
  name: string;
  employees: {
    id: number;
    name: string;
    salary: number;
  }[];
};

Here, both the keys in the Company type and the keys in the employees object type are sorted.

Best Practices

Consistent Sorting Style

Choose a sorting style (ascending or descending) and stick to it across the entire codebase. This ensures consistency and makes the code more predictable.

Use Pre-commit Hooks

To prevent unsorted keys from being committed to the repository, use a pre-commit hook. For example, with husky and lint-staged:

npm install --save-dev husky lint-staged
# or
yarn add --dev husky lint-staged

Then, add the following to your package.json:

{
  "husky": {
    "hooks": {
      "pre-commit": "lint-staged"
    }
  },
  "lint-staged": {
    "*.ts": ["eslint --fix", "git add"]
  }
}

This configuration will automatically fix the sorting issues before committing the code.

Conclusion

The eslint-plugin-typescript-sort-keys is a valuable tool for TypeScript developers to enforce a consistent sorting order for keys in objects and types. By following the usage methods, common practices, and best practices outlined in this blog post, you can improve the readability and maintainability of your TypeScript codebase.

References