Code Explainers

Code explainers tagged #persistence

typescript 
import { Injectable, effect, signal, computed } from '@angular/core';
 
interface Preferences {
  theme: 'light' | 'dark';

A signal-based preferences store in Angular

signals state-management persistence
Intermediate 7 steps
javascript 
import { createContext, useContext, useReducer, useCallback, useEffect } from 'react';
 
const AuthContext = createContext(null);
 

Building an auth context in React

context usereducer authentication
Intermediate 8 steps
typescript 
type CountdownState = {
  deadline: number;
  onTick: (remaining: number) => void;
  onComplete: () => void;

A countdown timer that survives reloads

persistence timers localstorage
Intermediate 10 steps
typescript 
type QueuedRequest = {
  id: string;
  url: string;
  method: string;

A retry queue with exponential backoff

retry exponential-backoff persistence
Intermediate 10 steps
javascript 
const STORAGE_KEY = "app_state";
const CURRENT_VERSION = 3;
 
const migrations = {

Versioned state migrations in localStorage

migrations persistence versioning
Intermediate 9 steps