bengrunfeld

FROM node:12.18.3

WORKDIR /usr/src/app

COPY package*.json ./

ENV MONGO_URL "mongodb://mongo:27017"
ENV DB_NAME points
ENV COL_NAME dataPoints

bengrunfeld

version: "2"

services:
  web:
    build:
      context: .
      dockerfile: Dockerfile
    container_name: web
    ports:
      - "4000:4000"

bengrunfeld

FROM node:12.18.3

WORKDIR /usr/src/app

ENV MESSAGE "Hello from Ben"

COPY package*.json ./

RUN npm install 

bengrunfeld

import { useState, useRef, forwardRef, useImperativeHandle } from "react";

const ChildOne = forwardRef((props, ref) => {
  const [count, setCount] = useState(0);

  useImperativeHandle(ref, () => ({
    count,
  }));

  const updateCount = () => {

bengrunfeld

import { useState, useMemo } from "react";

const data = [
  [93, 64, 60, 28, 17, 24, 36, 9, 47, 11, 80, 45],
  [87, 76, 66, 20, 18, 71, 5, 22, 36, 48, 28, 99],
  [3, 71, 62, 59, 22, 15, 33, 19, 13, 98, 98, 42],
];

const double = (arr) => {
  console.log("=> double", Date.now());

bengrunfeld

import { useState, useMemo } from "react";

const data = [
  [93, 64, 60, 28, 17, 24, 36, 9, 47, 11, 80, 45],
  [87, 76, 66, 20, 18, 71, 5, 22, 36, 48, 28, 99],
  [3, 71, 62, 59, 22, 15, 33, 19, 13, 98, 98, 42],
];

const double = (arr) => {
  // This shows that the function is being run on each render

bengrunfeld

import { useState, useCallback } from "react";

const CountDisplay = ({ count }) => <h3>Count: {count}</h3>;

const CountButton = React.memo(({ updateCount }) => {
  // Note that this line will now only execute once on initial render!
  console.log("=> CountButton render", Date.now());

  return <button onClick={() => updateCount()}>Increment</button>;
});

bengrunfeld

import { useState } from "react";

const CountDisplay = ({ count }) => <h3>Count: {count}</h3>;

const CountButton = ({ updateCount }) => {
  // Note that this line will fire every time, 
  // showing us that an unneeded re-render has occurred. 
  console.log("=> CountButton render", Date.now());

  return <button onClick={() => updateCount()}>Increment</button>;

bengrunfeld

// Find the min of an array
const a = [3, 8, 2, 99, 1, 42, 23]
Math.min.apply(Math, a)

// How to turn an array into an object
const a = [3, 8, 2, 99, 1, 42, 23]
const b = a.reduce((a, b, i) => {
  const obj = {}
  obj[i] = b

bengrunfeld

import { useRouter } from 'next/router'

const Post = ({ post }) => {
  const router = useRouter()

  if (router.isFallback) {
    return <div>Loading...</div>
  }

  return (