pickier/no-unused-vars

Reports variables and parameters that are declared/assigned but never used.

• Category: Plugin (built-in)
• Default: off

Options: { varsIgnorePattern?: string; argsIgnorePattern?: string } (defaults '^_' for both)

Config (both forms accepted):

pluginRules: {
  'no-unused-vars': ['error', { varsIgnorePattern: '^_', argsIgnorePattern: '^_' }],
  // or
  'pickier/no-unused-vars': ['error', { varsIgnorePattern: '^_', argsIgnorePattern: '^_' }],
}

Examples:

const unused = 1 // flagged
function greet(_name: string) {} // ok, matches '^_'

More examples

Destructuring:

const { used, unused } = api()
console.log(used)
// 'unused' is flagged unless ignored by pattern

Function parameters:

function run(used: number, _unused: number) {
  console.log(used)
}

Best practices

• Start with 'warn' to measure noise, then upgrade to 'error'
• Use ^_ prefix for intentionally unused names
• Avoid overly broad ignore patterns; prefer targeted prefixes to keep signal high
• Consider separate configs for tests to allow common unused patterns (e.g., _t in table-driven tests)