js-early-exit

---

name: js-early-exit description: Use early returns to avoid unnecessary computation in loops and functions. Apply when processing arrays, validating input, or checking multiple conditions where the result can be determined before all iterations complete.

Early Return from Functions

Return early when result is determined to skip unnecessary processing. This optimization is especially valuable when the skipped branch is frequently taken or when the deferred operation is expensive.

Incorrect (processes all items even after finding answer):

Copyfunction validateUsers(users: User[]) {
  let hasError = false
  let errorMessage = ''

  for (const user of users) {
    if (!user.email) {
      hasError = true
      errorMessage = 'Email required'
    }
    if (!user.name) {
      hasError = true
      errorMessage = 'Name required'
    }
    // Continues checking all users even after error found
  }

  return hasError ? { valid: false, error: errorMessage } : { valid: true }
}

Correct (returns immediately on first error):

Copyfunction validateUsers(users: User[]) {
  for (const user of users) {
    if (!user.email) {
      return { valid: false, error: 'Email required' }
    }
    if (!user.name) {
      return { valid: false, error: 'Name required' }
    }
  }

  return { valid: true }
}