turbod

type Email = string & { __brand: "Email" };
const email = "[email protected]";

function isValidEmail(input: string): input is Email {
  return /@/.test(input);
}

function sendEmail(email: Email) {
  console.log(email);
  // send email

turbod

type RgbTuple = Tuple<3, number>;
// ^? type RgbTuple = readonly [number, number, number]

const red: RgbTuple = [255, 0, 0];

type Tuple<Length, Type, Acc extends Type[] = []> = Acc["length"] extends Length
  ? Readonly<Acc>
  : Tuple<Length, Type, [...Acc, Type]>;

turbod

function add(a: number, b: number): number {
  return a + b;
}

type Test = typeof add;
// ^ = type Test = (a: number, b: number) => number
type Test2 = ReturnType<typeof add>;
// ^ = type Test2 = number
//

turbod

type Locations = 'Zurich' | 'Warsaw' | 'London';

function getCountryLocation(location: Locations) {
  switch (location) {
    case 'Zurich':
      return 'Switzerland';
    case 'Warsaw':
      return 'Poland';
    case 'London':
      return 'UK';

turbod

type GapType = 'margin' | 'padding';
type PositionType = 'top' | 'right' | 'bottom' | 'left';

type GapCss = `${GapType}-${PositionType}`;
// GapCss: "margin-top" | "margin-right" | "margin-bottom" | "margin-left" | "padding-top" | "padding-right" | "padding-bottom" | "padding-left"
// 


type SizeType = 'rem' | 'em' | 'px' | '%' | 'vh' | 'vw' | '';
type SizeCss = `${number}${SizeType}`;

turbod

type Events = {
  add: string;
  remove: string;
  move: string;
};

type EventKeys = keyof Events;

const userActions: OnEvent = {
  onAdd: () => {},

turbod

Intuition

Approach

Complexity

• Time complexity:

turbod

import { OtherComponent } from "./other-component";
import React, { useRef, ElementRef } from "react";

// Pass it in via typeof!
type OtherComponentRef = ElementRef<typeof OtherComponent>;

const Component = () => {
  const ref = useRef<OtherComponentRef>(null);
  return <OtherComponent ref={ref}>Hello</OtherComponent>;
};

turbod

import React, { forwardRef } from "react";

// Declare a type that works with generic components
type FixedForwardRef = <T, P = {}>(
render: (props: P, ref: React.Ref<T>) => React.ReactElement
) => (props: P & React.RefAttributes<T>) => React.ReactElement;

// Cast the old `forwardRef` to the new one
export const fixedForwardRef = forwardRef as FixedForwardRef;

turbod

# Sliding window algorithm
#
# @param {String} s
# @return {Integer}
def length_of_longest_substring(s)
  max = 0
  subset = []

  s.each_char do |char|
    if subset.include?(char)