/frontend-js-best-practices

Early Return from Functions

Return early when result is determined to skip unnecessary processing.

Incorrect (processes all items even after finding answer):

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 };
}

Correct (returns immediately on first error):

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 };
}