paulwongx

// SPDX-License-Identifier: MIT

pragma solidity ^0.8.0;

import "@openzeppelin/contracts/utils/cryptography/ECDSA.sol";

contract ECDSARecover {
    using ECDSA for bytes32;
    using ECDSA for bytes;

paulwongx

Devops

Source: https://www.youtube.com/watch?v=Wvf0mBNGjXY

Linux commands

$ echo $SHELL
>> shellvar

$ pwd
>> /home/my_dir1

paulwongx

import crypto from "crypto";
import fs from "fs";

// Creates a sha256 hash from a file
export const createHashFromFile = (filePath: string) => new Promise(resolve => {
  const hash = crypto.createHash('sha256');
  fs.createReadStream(filePath).on('data', data => hash.update(data)).on('end', () => resolve(hash.digest('hex')));
});

paulwongx

Javascript Cheatsheet

1. This document focuses on more nuanced topics. It is not comprehensive.
2. Examples are taken from MDN mostly

Strings

// [@@iterator]() - iterating a string
const str = 'A\uD835\uDC68';
const strIter = str[Symbol.iterator]();

paulwongx

VSCode Shortcuts

Windows Shortcut	MacOS	Function
Alt + Up/Down Arrow	Opt + Up/Down Arrow	Moves line of code up or down
Alt + Shift + Up/Down Arrow	Opt + Shift + Up/Down Arrow	Duplicates line of code
Ctrl + P	Cmd + P	Search and open a file quickly
Ctrl + Shift + P	Cmd + Shift + P	Open up the command prompt
Alt + Shift + F	Shift + Opt + F	Format document
Ctrl + Shift + F	Shift + Cmd + F	Search for file
Ctrl + Shift + E	Shift + Cmd + E	Open up file explorer

paulwongx

import { PrismaClient } from "@prisma/client"
const prisma = new PrismaClient()
// const prisma = new PrismaClient({ log: ["query"]})

// npx prisma generate
// to generate the types, if not, close and re-open file. If not, ctrl+click create to reload typescript

// npx prisma migrate dev --name test2

async function main() {

paulwongx

Sorting Algorithms

Reference \

Straight Insertion

Description - From left to right, sort the numbers in groups starting from 1 to the length of the array
Time complexity - O(n^2)
Space complexity - O(1)

paulwongx

import ytdl from "ytdl-core";
import fs from "fs";
import ffmpeg from "fluent-ffmpeg";
import readline from "readline";

// https://github.com/fent/node-ytdl-core/blob/master/example/convert_to_mp3.js

const id = 'nMfPqeZjc2c';

let stream = ytdl(id, {

paulwongx

"use client"
import React, { useState, SetStateAction, Dispatch } from "react";
import { Color, colors } from "@/types"
import { useIsomorphicLayoutEffect } from "usehooks-ts";

interface ThemeContextProps {
  theme: Color;
  setTheme: Dispatch<SetStateAction<Color>> | null;
}

paulwongx

# Creating a next app from example template
# All examples: https://github.com/vercel/next.js/tree/canary/examples
yarn create next-app -e app-dir-mdx .