@omneedia/auth-js/src/lib/helpers.ts

Isomorphic Auth client

import { SupportedStorage } from './types'

export function expiresAt(expiresIn: number) {
  const timeNow = Math.round(Date.now() / 1000)
  return timeNow + expiresIn
}

export function uuid() {
  return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
    const r = (Math.random() * 16) | 0,
      v = c == 'x' ? r : (r & 0x3) | 0x8
    return v.toString(16)
  })
}

export const isBrowser = () => typeof document !== 'undefined'

export function getParameterByName(name: string, url?: string) {
  if (!url) url = window?.location?.href || ''
  // eslint-disable-next-line no-useless-escape
  name = name.replace(/[\[\]]/g, '\\$&')
  const regex = new RegExp('[?&#]' + name + '(=([^&#]*)|&|#|$)'),
    results = regex.exec(url)
  if (!results) return null
  if (!results[2]) return ''
  return decodeURIComponent(results[2].replace(/\+/g, ' '))
}

type Fetch = typeof fetch

export const resolveFetch = (customFetch?: Fetch): Fetch => {
  let _fetch: Fetch
  if (customFetch) {
    _fetch = customFetch
  } else if (typeof fetch === 'undefined') {
    _fetch = async (...args) => await (await import('cross-fetch')).fetch(...args)
  } else {
    _fetch = fetch
  }
  return (...args) => _fetch(...args)
}

export const looksLikeFetchResponse = (maybeResponse: unknown): maybeResponse is Response => {
  return (
    typeof maybeResponse === 'object' &&
    maybeResponse !== null &&
    'status' in maybeResponse &&
    'ok' in maybeResponse &&
    'json' in maybeResponse &&
    typeof (maybeResponse as any).json === 'function'
  )
}

// Storage helpers
export const setItemAsync = async (
  storage: SupportedStorage,
  key: string,
  data: any
): Promise<void> => {
  await storage.setItem(key, JSON.stringify(data))
}

export const getItemAsync = async (storage: SupportedStorage, key: string): Promise<unknown> => {
  const value = await storage.getItem(key)

  if (!value) {
    return null
  }

  try {
    return JSON.parse(value)
  } catch {
    return value
  }
}

export const removeItemAsync = async (storage: SupportedStorage, key: string): Promise<void> => {
  await storage.removeItem(key)
}

export const decodeBase64URL = (value: string): string => {
  try {
    // atob is present in all browsers and nodejs >= 16
    // but if it is not it will throw a ReferenceError in which case we can try to use Buffer
    // replace are here to convert the Base64-URL into Base64 which is what atob supports
    // replace with //g regex acts like replaceAll
    // Decoding base64 to UTF8 see https://stackoverflow.com/a/30106551/17622044
    return decodeURIComponent(
      atob(value.replace(/[-]/g, '+').replace(/[_]/g, '/'))
        .split('')
        .map((c) => '%' + ('00' + c.charCodeAt(0).toString(16)).slice(-2))
        .join('')
    )
  } catch (e) {
    if (e instanceof ReferenceError) {
      // running on nodejs < 16
      // Buffer supports Base64-URL transparently
      return Buffer.from(value, 'base64').toString('utf-8')
    } else {
      throw e
    }
  }
}

/**
 * A deferred represents some asynchronous work that is not yet finished, which
 * may or may not culminate in a value.
 * Taken from: https://github.com/mike-north/types/blob/master/src/async.ts
 */
export class Deferred<T = any> {
  public static promiseConstructor: PromiseConstructor = Promise

  public readonly promise!: PromiseLike<T>

  public readonly resolve!: (value?: T | PromiseLike<T>) => void

  public readonly reject!: (reason?: any) => any

  public constructor() {
    // eslint-disable-next-line @typescript-eslint/no-extra-semi
    ;(this as any).promise = new Deferred.promiseConstructor((res, rej) => {
      // eslint-disable-next-line @typescript-eslint/no-extra-semi
      ;(this as any).resolve = res
      // eslint-disable-next-line @typescript-eslint/no-extra-semi
      ;(this as any).reject = rej
    })
  }
}

// Taken from: https://stackoverflow.com/questions/38552003/how-to-decode-jwt-token-in-javascript-without-using-a-library
export function decodeJWTPayload(token: string) {
  // Regex checks for base64url format
  const base64UrlRegex = /^([a-z0-9_-]{4})*($|[a-z0-9_-]{3}=?$|[a-z0-9_-]{2}(==)?$)$/i

  const parts = token.split('.')

  if (parts.length !== 3) {
    throw new Error('JWT is not valid: not a JWT structure')
  }

  if (!base64UrlRegex.test(parts[1])) {
    throw new Error('JWT is not valid: payload is not in base64url format')
  }

  const base64Url = parts[1]
  return JSON.parse(decodeBase64URL(base64Url))
}