Subchapter 3.31

Js Early Exit

rules/js-early-exit.mdMarkdown1 KBView on GitHub

Early Return from Functions

Return early when result is determined to skip unnecessary processing.

Incorrect (processes all items even after finding answer):

Js Early Exit · Vercel React Best Practices · vercel-labs/agent-skills · Skills Docs

function 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 }
}

function 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 }
}