Ryota Yamamoto Restoration

non-null assertion operator

https://stackoverflow.com/questions/40349987/how-to-suppress-typescript-error-ts2533-object-is-possibly-null-or-undefine

If you know from external means that an expression is not null or undefined, you can use the non-null assertion operator ! to coerce away those types:

// Error, some.expr may be null or undefined
let x = some.expr.thing;
// OK
let y = some.expr!.thing;

	// https://github.com/DefinitelyTyped/DefinitelyTyped/issues/31125
	interface ExpressNextContext extends NextContext {
	req?: express.Request;
	res?: express.Response;
	}

	class Page extends React.Component {
	static getInitialProps(ctx: ExpressNextContext) {
	...

	import React from 'react';
	import ReactDOM from 'react-dom';
	import './index.css';
	const productsList = [
	{
	sku: "first_product",
	title: "Fishsticks",
	price: 8.99
	},
	{

	// https://www.simplethread.com/cant-replace-redux-with-hooks/
	import React, { createContext, useReducer, useContext } from 'react';

	const defaultState = {
	counter: 0,
	};

	function reducer(state = defaultState, action = {}) {
	switch (action.type) {
	case 'COUNTER_INC':

	// https://www.sitepoint.com/replace-redux-react-hooks-context-api/

	// Define the initial state of our app
	const initialState = {
	contacts: [
	{
	id: "098",
	name: "Diana Prince",
	email: "[email protected]"
	},

	useEffect(() => {
	window.addEventListener('mousemove', () => {});

	// returned function will be called on component unmount
	return () => {
	window.removeEventListener('mousemove', () => {})
	}
	}, [])

	# http://webrocketsmagazine.com/entry/20120203/css3-bevel.html
	/* CSS3でボックスの角にベベル（丸くないborder-radius）をかける方法 */
	.bevel {
	background:
	linear-gradient(45deg, transparent 10px, #0099ff 10px),
	linear-gradient(135deg, transparent 10px, #0099ff 10px),
	linear-gradient(225deg, transparent 10px, #0099ff 10px),
	linear-gradient(315deg, transparent 10px, #0099ff 10px);
	background-position: bottom left, bottom right, top right, top left;
	background-size: 50% 50%;

	# https://docs.docker.com/compose/wordpress/
	version: '3.3'

	services:
	db:
	image: mysql:5.7
	volumes:
	- db_data:/var/lib/mysql
	restart: always
	environment:

	/*
	3
	11 2 4
	4 5 6
	10 8 -12
	*/


	//11 + 5 -12 = 4
	//4 + 5 + 10 = 19

	( async ( ) => {
	await console.log("Hello");
	})();