szaranger

document.querySelector('#myButton').addEventListener('click', e => { 
	e.currentTarget; // Type is EventTarget
	const button = e.currentTarget as HTMLButtonElement; // buttonType is HTMLButtonElement
});

szaranger

type Person = { name: string }; 

const john: Person = {  
  name: 'John',  
  dob: '05/09/1982'    
  // Object literal may only specify known properties and     
  // 'dob' does not exist in type 'Person'  
};  

const jane = {  

szaranger

const john: Person = {}; // Error
const jane = {} as Person; // No error

szaranger

type Person = { name: string };  

const john: Person = { name: 'John Doe' }; // Type declaration 
const jane = { name: 'Jane Doe' } as Person; // Type assertion

szaranger

const promises = await settledPromises;
promises; // [{ status: '...', value: '...' }, ...]

szaranger

async function run() {
  const settledPromises = Promise.allSettled([
    new Promise((r, reject) => setTimeout(() => reject("Out of stock"), delay)),
    new Promise((r, reject) => setTimeout(() => reject("Out of stock"), delay))
  ]);
  
  // wait...
  const promises = await settledPromises;
  
  // after 0.8 seconds

szaranger

async function run() {
  const settledPromises = Promise.allSettled([
    new Promise((resolve) => setTimeout(() => resolve(["shirts", "trousers"]), 800)),
    new Promise((r, reject) => setTimeout(() => reject("Out of stock"), delay))
  ]);
  
  // wait...
  const promises = await settledPromises;
  
  // after 0.8 seconds

szaranger

async function run() {
  const settledPromises = Promise.allSettled([
    new Promise((resolve) => setTimeout(() => resolve(["shirts", "trousers"]), 800)),
    new Promise((resolve) => setTimeout(() => resolve(["sneakers", "boots"]), 800)),
  ]);
  
  // wait...
  const promises = await settledPromises;
  
  // after 0.8 seconds

szaranger

import { useMemo, useState } from "react";

function Child({ total }) {
  return <p>{`Total: ${total}`}</p>;
}

export default function Parent() {
  const [a, setA] = useState(0);
  const [b, setB] = useState(0);
  

szaranger

function calc(x, y) {
  return x + y;
}

const memoizedValue = useMemo(() => {
  return calc(a, b);
}, [a, b]);