tsr

tsr

TypeScript Remove (tsr) is a utility that removes unused code from TypeScript projects – It's like tree shaking, but for source files

Features

• 🛠️ Auto-fix unused exports — removes the export keyword from the declaration or the whole declaration based on its usage
• 🧹 Deletes TypeScript modules that have no referenced exports
• 🕵️ Check – Use the command without --write to detect unused code without making changes

Install

npm i tsr

TypeScript is a peer dependency.

Quick Start

1. 🔍 Check your tsconfig.json – Make sure include and exclude is configured thoroughly so that we can correctly detect what's "unused" in your project.

2. 🔍 Check your entrypoint files – What's the file that is the starting point for your code? Without this information, all files will be recognized as unnecessary. Usually it is some file like src/main.ts or maybe a group of files like src/pages/*.

3. 🚀 Execute – Pass a regex (or multiple regex patterns) that match the entrypoints. Use --write to change the files in place.

npx tsr 'src/main\.ts$'

Examples

Here are some examples of how this tool will auto-fix unused code.

When a2 is not used within the project:

--- src/a.ts
+++ src/a.ts
@@ -1,3 +1 @@
 export const a = 'a';
-
-export const a2 = 'a2';

When b is not used within the project but f() is used within the project:

--- src/b.ts
+++ src/b.ts
@@ -1,5 +1,5 @@
-export const b = 'b';
+const b = 'b';
 
 export function f() {
     return b;
 }

When f() is not used within the project and when deleting it will result in import being unnecessary:

--- src/c.ts
+++ src/c.ts
@@ -1,7 +1 @@
-import { cwd } from "node:process";
-
 export const c = 'c';
-
-export function f() {
-    return cwd();
-}

When f() and exported are not used within the project and when deleting f() will result in exported and local being unnecessary:

--- src/d.ts
+++ src/d.ts
@@ -1,8 +1 @@
-export const exported = "exported";
-const local = "local";
-
 export const d = "d";
-
-export function f() {
-  return { exported, local };
-}

In addition to the behavior shown in the examples above, tsr will delete files that have no used exports.

tsr works with all kinds of code: variables, functions, interfaces, classes, type aliases and more!

Usage

Options

Usage:
  $ tsr [...entrypoints]

Commands:
  [...entrypoints]  regex patterns to match entrypoints

For more info, run any command with the `--help` flag:
  $ tsr --help

Options:
  -p, --project <file>  Path to your tsconfig.json 
  -w, --write           Write changes in place 
  -r, --recursive       Recursively look into files until the project is clean 
  --include-d-ts        Check for unused code in .d.ts files 
  -h, --help            Display this message 
  -v, --version         Display version number 

Examples:
npx tsr 'src/main\.ts$'

-p, --project

Specifies the tsconfig.json that is used to analyze your codebase. Defaults to tsconfig.json in your project root.

npx tsr --project tsconfig.client.json

-w, --write

Writes fixable changes in place.

[!WARNING] This will delete code. Using it in a git controlled environment is highly recommended.

-r, --recursive

The default behavior of the CLI is to process all files once. Some issues may not be detected if the unused code is a result of the modification of another file in the project. When this option is enabled, tsr will recursively re-edit/re-check files that may be affected by a file edit.

This will take longer but is helpful when you want to edit in one pass.

--include-d-ts

By default, exported types in .d.ts files are not detected. Use the --include-d-ts option if you want to include types in .d.ts files

Use the JavaScript API

Alternatively, you can use the JavaScript API to execute tsr.

import { tsr } from 'tsr';

await tsr({
  entrypoints: [/main\.ts/],
  mode: 'check',
});

Skip

When you add a comment // tsr-skip to your export declaration, it will be skipped from being removed

// tsr-skip
export const hello = 'world';

Handling test files

If you have a separate tsconfig for tests using Project References, that would be great! tsr will remove exports/files that exist for the sake of testing.

If you pass a tsconfig.json to the CLI that includes both the implementation and the test files, tsr will remove your test files since they are not referenced by your entry point file by default. You can avoid tests being deleted by passing a pattern that matches your test files to the args in the meantime, but the recommended way is to use project references to ensure your TypeScript config is more robust and strict (not just for using this tool).

npx tsr -w 'src/main\.ts$' ## depending on the tsconfig, this will delete test files
npx tsr -w 'src/main\.ts$' '.*\.test\.ts$' ## Specifying test files as entrypoints will avoid deletion

Comparison

TypeScript

If you enable compilerOptions.noUnusedLocals, declarations that are never read will be reported.

// 'a' is declared but its value is never read.
const a = 'a';

However, when you export it, no errors will be reported regardless of its usage within the project. tsr's aim is to report/fix unused code while taking project wide usage into account.

ESLint

ESLint will detect unused imports. Plugins such as eslint-plugin-unused-imports can also auto-fix this issue.

// 'foo' is defined but never used.
import { foo } from './foo';

However, we can't detect unused exports. ESLint's architecture works in a file by file basis and was never intended to provide linting based on project-wide usage stats.

// a lint rule that detects if this export is used within the project is unlikely to be introduced
export const a = 'a';

tsr's main goal is to remove unused exports and delete unused modules, but it will also delete unused imports that are a result of removing an export declaration.

Author

Kazushi Konosu (https://github.com/kazushisan)

Contributing

Contributions are welcomed!

License

Copyright (C) 2023 LINE Corp.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.