oleh-zaporozhets

...
constructor(http: IHttp, options: ICircuitBreakerOptions) {
  this.http = http;
  this.timeout = options.timeout;
  this.errorHandler = options.errorHandler;

  this.http.instance.interceptors.request.use(this.interceptRequest.bind(this));
  this.http.instance.interceptors.response.use(
    (response: AxiosResponse) => response,
    this.interceptErrorResponse.bind(this),

oleh-zaporozhets

...
private interceptRequest(config: AxiosRequestConfig) {
  const CancelToken = axios.CancelToken;

  const cancelToken = new CancelToken((cancel) => cancel('Circuit breaker is open'));

  return {
    ...config,
    ...(this.isOpen ? { cancelToken } : {}),
  };

oleh-zaporozhets

...
private interceptErrorResponse(error: any) {
  const shouldCircuitBreakerBeOpen = this.errorHandler(error);

  if (shouldCircuitBreakerBeOpen && !this.isOpen) {
    this.openCircuitBreaker();
  }

  return Promise.reject(error);
}

oleh-zaporozhets

class CircuitBreaker implements ICircuitBreaker {
	private readonly http: IHttp;
	private readonly timeout: number;
	private isOpen = false;
	private errorHandler: (error: any) => boolean;
	
	constructor(http: IHttp, options: ICircuitBreakerOptions) {
	  this.http = http;
	  this.timeout = options.timeout;
	  this.errorHandler = options.errorHandler;

oleh-zaporozhets

class UsefulService extends Http {
  constructor() {
    super('https://3rd-party.com/');
  }

  public getInfo() {
    return this.instance.get('/useful-information');
  }
}

oleh-zaporozhets

import axios, { AxiosInstance } from 'axios';

class Http implements IHttp {
  public readonly instance: AxiosInstance;

  constructor(baseURL: string) {
    this.instance = axios.create({ baseURL });
  }
}

oleh-zaporozhets

import Storage from './storage';

enum Locals {
  ACCESS_TOKEN = 'access_token',
  REFRESH_TOKEN = 'refresh_token'
}

export default class Tokens extends Storage<Locals> {
  private static instance?: Tokens;

oleh-zaporozhets

public clear() {
  this.clearItems([Locals.ACCESS_TOKEN, Locals.REFRESH_TOKEN]);
}

oleh-zaporozhets

public getRefreshToken() {
  return this.get(Locals.REFRESH_TOKEN);
}

public setRefreshToken(refreshToken: string) {
  this.set(Locals.REFRESH_TOKEN, refreshToken);
}

oleh-zaporozhets

public getAccessToken() {
  return this.get(Locals.ACCESS_TOKEN);
}

public setAccessToken(accessToken: string) {
  this.set(Locals.ACCESS_TOKEN, accessToken);
}