JavaScript Advanced Cheat Sheet

function getData() {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve("Obtained data");
    }, 1000);
  });
}

getData()
  .then(data => console.log(data)) // Output: Obtained data (after 1 second)
  .catch(error => console.error(error));

// file: module.js
export function greet(name) {
     console.log(`Hello, ${name}!`);
}

// file: main.js
import { greet } from './module.js';
greet('Bob'); // Output: Hello, Bob!

//SAVING
const sessionToken = 'abcdef12345';
sessionStorage.setItem('sessionToken', sessionToken);
console.log('Session token saved to sessionStorage.');

//RETRIEVING
const storedToken = sessionStorage.getItem('sessionToken');
if (storedToken) {
  console.log('Session token retrieved from sessionStorage:', storedToken);
} else {
  console.log('No session token found.');
}


//SAVING and RETRIEVING a temporary object
const currentOrderStatus = {
  orderId: 123,
  status: 'pending'
};
sessionStorage.setItem('orderStatus', JSON.stringify(currentOrderStatus));
console.log('Order status saved to sessionStorage.');

const storedOrderStatus = sessionStorage.getItem('orderStatus');
if (storedOrderStatus) {
  const parsedStatus = JSON.parse(storedOrderStatus);
  console.log('Order status retrieved from sessionStorage:', parsedStatus);
  console.log('Current status:', parsedStatus.status);
}


//Removing a specific session item
sessionStorage.removeItem('sessionToken');
console.log('Session token removed from sessionStorage.');


//Clearing all session items
sessionStorage.clear();
console.log('All items cleared from sessionStorage.');

async function getDataAsync() {
  try {
    const data = await getData(); //getData() is a Promise
    console.log(data); // Output: Obtained data (after 1 second)
  } catch (error) {
    console.error(error);
  }
}

getDataAsync();

const username = "JohnDoe";
localStorage.setItem('username', username);
console.log('Username saved to localStorage.');

const storedUsername = localStorage.getItem('username');
if (storedUsername) {
  console.log('Username retrieved from localStorage: ', storedUsername);
} else {
  console.log('No username found in localStorage.');
}


//SAVING OBJECT requires stringify
const userSettings = {
  theme: 'dark',
  fontSize: '16px',
  notificationsEnabled: true
};
localStorage.setItem('userSettings', JSON.stringify(userSettings));
console.log('User settings saved to localStorage.');


//RETRIEVING OBJECT needs to be parsed
const storedSettings = localStorage.getItem('userSettings');
if (storedSettings) {
  const parsedSettings = JSON.parse(storedSettings);
  console.log('User settings retrieved from localStorage: ', parsedSettings);
  console.log('Current theme: ', parsedSettings.theme);
} else {
  console.log('No user settings found in localStorage.');
}


//Removing a specific local item
localStorage.removeItem('username');
console.log('User after removal:', localStorage.getItem('theme')); // Output: User after removal: null


//Clearing all local items
localStorage.clear();
console.log('Items in localStorage after clear:', localStorage); // Output: Storage {length: 0}