eslint/default-case Restriction

What it does

Enforces that all switch statements include a default case, unless explicitly marked with a configured comment.

Why is this bad?

Without a default case, it is unclear whether the omission was intentional or an oversight. Adding a default or a special comment makes the code more explicit and reduces mistakes.

You may optionally include a // no default after the last case if there is no default case. The comment may be in any desired case, such as // No Default.

Options

First option:

• Type: object
• Properties:
  • commentPattern: string (default: /^no default$/i) - A regex pattern used to detect comments that mark the absence of a default case as intentional.

Example configuration:

{
  "default-case": ["error", { "commentPattern": "^skip\\sdefault" }]
}

Examples of incorrect code for this rule:

/* default-case: ["error"] */

switch (foo) {
  case 1:
    break;
}

Examples of correct code for this rule:

/* default-case: ["error"] */

switch (a) {
  case 1:
    break;
  default:
    break;
}

switch (a) {
  case 1:
    break;
    // no default
}

commentPattern

Examples of incorrect code for this rule with the { "commentPattern": "^skip\\sdefault" } option:

/* default-case: ["error", { "commentPattern": "^skip\\sdefault" }] */

switch (a) {
  case 1:
    break;
    // no default
}

Examples of correct code for this rule with the { "commentPattern": "^skip\\sdefault" } option:

/* default-case: ["error", { "commentPattern": "^skip\\sdefault" }] */

switch (a) {
  case 1:
    break;
    // skip default
}

How to use

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

CLI

oxlint --deny default-case

Config (.oxlintrc.json)

{
  "rules": {
    "default-case": "error"
  }
}

References

• Rule Source