unicorn/filename-case Style

What it does

Enforces a consistent case style for filenames to improve project organization and maintainability. By default, kebab-case is enforced, but other styles can be configured.

Files named index.js, index.ts, etc. are exempt from this rule as they cannot reliably be renamed to other casings (mainly just a problem with PascalCase).

Why is this bad?

Inconsistent file naming conventions make it harder to locate files, navigate projects, and enforce consistency across a codebase. Standardizing naming conventions improves readability, reduces cognitive overhead, and aligns with best practices in large-scale development.

Examples

Examples of correct filenames for each case:

kebabCase

• some-file-name.js
• some-file-name.test.js
• some-file-name.test-utils.js

camelCase

• someFileName.js
• someFileName.test.js
• someFileName.testUtils.js

snakeCase

• some_file_name.js
• some_file_name.test.js
• some_file_name.test_utils.js

pascalCase

• SomeFileName.js
• SomeFileName.Test.js
• SomeFileName.TestUtils.js

Configuration

This rule accepts a configuration object with the following properties:

case

type: "kebabCase" | "camelCase" | "snakeCase" | "pascalCase"

default: "kebabCase"

The case style to enforce for filenames.

You can set the case option like this:

"unicorn/filename-case": [
"error",
{
"case": "kebabCase"
}
]

cases

type: object

default: {"kebabCase":true, "camelCase":false, "snakeCase":false, "pascalCase":false}

The case style(s) to allow/enforce for filenames. true means the case style is allowed, false means it is banned.

You can set the cases option like this:

"unicorn/filename-case": [
"error",
{
"cases": {
"camelCase": true,
"pascalCase": true
}
}
]

cases.camelCase

type: boolean

default: false

Whether camel case is allowed, e.g. someFileName.js.

cases.kebabCase

type: boolean

default: true

Whether kebab case is allowed, e.g. some-file-name.js.

cases.pascalCase

type: boolean

default: false

Whether pascal case is allowed, e.g. SomeFileName.js.

cases.snakeCase

type: boolean

default: false

Whether snake case is allowed, e.g. some_file_name.js.

ignore

type: string | null

A regular expression pattern for filenames to ignore.

You can set the ignore option like this:

"unicorn/filename-case": [
"error",
{
"ignore": "^foo.*$"
}
]

multipleFileExtensions

type: boolean

default: true

Whether to treat additional, .-separated parts of a filename as parts of the extension rather than parts of the filename.

How to use

To enable this rule using the config file or in the CLI, you can use:

Config (.oxlintrc.json)

{
  "rules": {
    "unicorn/filename-case": "error"
  }
}

CLI

oxlint --deny unicorn/filename-case

References

• Rule Source