Ever Dev ever-dev

We often face (or sometimes we need to implement) initialValue which sets the value only for the first time when it's rendered. (Fortunately, I had a chance to implement initialValue not so long ago).
A good example is formik.

const [types, setTypes] = useEffect(null);
const getTypes = useCallback(async () => {
  const res = await getTypesAPI();
  setTypes(res);
}, []);
return

Use of callback like functions

function someFunction1( callbackFn ) => someFunction1(() => { doSomething(); })

function promiseFunction() {
  return new Promise((resolve) => {
     someFunction1(resolve);
  });
}

	/** @jsx jsx */
	import { jsx, css } from '@emotion/core'
	import { FunctionComponent, useState } from 'react'
	import { Icon } from '~/components'
	import PerfectScrollbar from 'react-perfect-scrollbar'
	import 'react-perfect-scrollbar/dist/css/styles.css'

	interface Tab {
	title: string
	Content: FunctionComponent<{}>

	function promiseFunction(v) {
	return new Promise((resolve) => {
	setTimeout(() => resolve(v), 1000);
	});
	}

	// f1() will print `all done` first and then print 1,2,3,4 at once after a second.
	function f1() {
	[1, 2, 3, 4]. forEach(async(i) => {
	const v = await promiseFunction(i);

	type THttpMethod = "GET" \| "POST" \| "PUT" \| "DELETE";

	export const httpClient = (
	url: string,
	method: THttpMethod = "GET",
	data: any = {}
	) => {
	const params: { [i: string]: any } = {
	method,
	headers: {

	import { useState, useEffect } from "react";

	export const useTimer = (delay: number) => {
	const [clock, setClock] = useState(false);

	useEffect(
	() => {
	// toggle clock
	const handler = setInterval(() => {
	setClock((v) => !v);

	import { useState, useEffect } from "react";

	export const useDebounce = (value: any, delay: number) => {
	// State and setters for debounced value
	const [debouncedValue, setDebouncedValue] = useState(value);

	useEffect(
	() => {
	// Update debounced value after delay
	const handler = setTimeout(() => {

	using Microsoft.Extensions.Options;
	using System.Threading.Tasks;
	using Twilio;
	using Twilio.Rest.Api.V2010.Account;
	using Twilio.Types;

	namespace Web2FA.Services
	{
	// This class is used by the application to send Email and SMS
	// when you turn on two-factor authentication in ASP.NET Identity.

	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<meta http-equiv="X-UA-Compatible" content="ie=edge">
	<title>Document</title>
	</head>
	<body>

	// flatten the array of integers

	const flatten = array =>
	JSON.stringify(array) // JSON encode the array to make string
	.match(/\d+/g) // extract numbers using regex
	.map(x => parseInt(x)); // convert string to numbers


	// unit testing with Mocha
	var assert = require('assert');