SZharkov’s gists

SZharkov / WebSocketProvider.js

Created July 11, 2023 08:30

WebSocket for ethers to avoid stop working in some time

	import { ethers } from 'ethers';

	const WEBSOCKET_PING_INTERVAL = 10000
	const WEBSOCKET_PONG_TIMEOUT = 5000
	const WEBSOCKET_RECONNECT_DELAY = 100

	const WebSocketProviderClass = () => class {}

	export class WebSocketProvider extends WebSocketProviderClass() {
	events = []

SZharkov / index.js

Created April 24, 2023 15:57

Websocket Stream with Ethers.js

	class WebsocketStream {
	static EXPECTED_PONG_BACK = 10000;
	static KEEP_ALIVE_CHECK_INTERVAL = 5000;
	pingTimeout = null;
	keepAliveInterval = null;
	provider;
	providerWss;

	constructor() {
	this.provider = new ethers.providers.JsonRpcProvider(

SZharkov / mongoose-two-fields-unique.js

Created April 7, 2023 08:06

Mongoose: make a combination of two fields unique

person.index({ firstName: 1, lastName: 1}, { unique: true });

SZharkov / mongoose-remove-duplicates.js

Created April 7, 2023 08:03

Remove duplicates in MongoDB with mongoose

-db.table.aggregate([
- {
-     "$group": {
-         _id: {slug: "$slug"},
-         slugs: { $addToSet: "$_id" } ,
-         count: { $sum : 1 }
-     }
- },
- {
-     "$match": {

SZharkov / parallelPromises.js

Created December 23, 2022 21:50

	async function fetchUserResources() {
	const [posts, photos, todos] = await Promise.allSettled([
	fetch('https://jsonplaceholder.typicode.com/posts/1'),
	fetch('https://jsonplaceholder.typicode.com/photos/1'),
	fetch('https://jsonplaceholder.typicode.com/todos/1')
	]);

	console.log(posts);
	// {status: "fulfilled", value: {"holds_the_posts_object"}}

SZharkov / almostIncreasingSequence.js

Created September 27, 2020 16:06 — forked from ryanSN/almostIncreasingSequence.js

Javascript almost increasing sequence

	function almostIncreasingSequence(sequence) {
	var found = false;
	for (var i=0;i<sequence.length;i++) {
	if(sequence[i] <= sequence[i-1]) {
	if(found) {
	return false;
	}
	found = true;

	if(i === 1 \|\| i + 1 === sequence.length) {

SZharkov / sitemap.js

Created August 23, 2020 10:47 — forked from emilpriver/sitemap.js

	// import functions from the package
	import { SitemapStream, streamToPromise } from "sitemap";

	// A custom function I use to fetch data from a backend. I will keep the import to make it more clear why "graphlqlFetch" is used in the code
	import graphlqlFetch from "lib/apollo"

	export default async (req, res) => {
	// Fetch data from a source which will be used to render the sitemap.
	const { posts } = await graphlqlFetch(`
	query getSitemapData {

SZharkov / index.js

Created August 2, 2020 11:04

Next.js ClientOnlyPortal

	import { useRef, useEffect, useState } from 'react'
	import { createPortal } from 'react-dom'

	export default function ClientOnlyPortal({ children, selector }) {
	const ref = useRef()
	const [mounted, setMounted] = useState(false)

	useEffect(() => {
	ref.current = document.querySelector(selector)
	setMounted(true)

SZharkov / actions.js

Last active March 27, 2022 01:53

Context API store

	import {
	ADD_INGREDIENT,
	INGREDIENTS_REDUCER,
	PREPARING_REDUCER,
	REMOVE_INGREDIENT,
	SET_INGREDIENT_INPUT_VALUE, SET_INPUT_VALUE, SET_OPTIONAL,
	SET_SELECTED_INGREDIENT,
	} from "Store/add-new-dish/types";

	const useAddNewDishActions = dispatch => {

SZharkov / index.js

Created January 21, 2020 17:33

Basic authentication with fetch

	// Node
	headers.set('Authorization', 'Basic ' + Buffer.from(username + ":" + password).toString('base64'));

	// Browser
	headers.set('Authorization', 'Basic ' + btoa(username + ":" + password));

Serhii SZharkov