Function execOnce

packages/eslint-plugin-next/src/utils/url.ts:178–191

(
  fn: (...args: TArgs) => TResult
)

}

export function execOnce<TArgs extends any[], TResult>(
  fn: (...args: TArgs) => TResult
): (...args: TArgs) => TResult {
  let used = false
  let result: TResult

  return (...args: TArgs) => {
    if (!used) {
      used = true
      result = fn(...args)
    }
    return result
  }
}

function ensureLeadingSlash(route: string) {
  return route.startsWith('/') ? route : `/${route}`