Kevin Coyner kcoyner

Front and back end web, sysadmin, and Debian developer.

kcoyner / react_lazy_retry.js

Created January 21, 2021 03:42

retry when loading a chunk fails

	/* If the browser fails to download the module, it'll try again
	* 5 times with a 1 second delay between each attempt. If
	* even after 5 tries it fails to import it, then an error is thrown.
	*/

	export function retry(fn, retriesLeft = 5, interval = 1000) {
	return new Promise((resolve, reject) => {
	fn()
	.then(resolve)
	.catch((error) => {

kcoyner / useContext.js

Created January 19, 2021 12:11

example of useContext

	import React, { useState } from 'react';

	// Create a Context
	const MyContext = React.createContext();
	// It returns an object with 2 values: { Provider, Consumer }

	function ParentComponent() {
	const [counter, setCounter] = useState(0);

	// Create an object containing both the value and the setter

kcoyner / styled-component

Last active November 11, 2020 03:01

styled-component

	import styled, { css } from 'styled-components';
	import React from 'react';

	interface Border extends React.HTMLAttributes<HTMLElement> {
	isInEdit: boolean;
	}

	const border = css<Border>`
	border: 1px solid ${({ isInEdit }) => (isInEdit ? 'red' : 'transparent')};
	&:hover {

kcoyner / rspam-whitelisting.md

Last active June 26, 2020 12:02

Whitelisting for rspamd

/etc/rspamd/local.d/multimap.conf:

IP_WHITELIST {
      type = "ip";
      prefilter = true;
      map = "/${LOCAL_CONFDIR}/local.d/ip_whitelist.map";
      action = "accept";
}

kcoyner / index.html

Created April 25, 2020 14:59

Sticky Footer using Flexbox

kcoyner / compare-useEffect-useMemo.js

Created December 13, 2019 17:37

useState/useEffect vs useMemo - essentially equivalent

	// useEffect & useState
	const useCalculate = numberProp => {
	const [result, setResult] = useState<number>(null);

	useEffect(() => {
	setResult(expensiveCalculation(numberProp));
	}, [numberProp]);

	return result;
	};

kcoyner / compare-useEffect-useMemo.js

Created December 13, 2019 17:37

useState/useEffect vs useMemo - essentially equivalent

	// useEffect & useState
	const useCalculate = numberProp => {
	const [result, setResult] = useState<number>(null);

	useEffect(() => {
	setResult(expensiveCalculation(numberProp));
	}, [numberProp]);

	return result;
	};

kcoyner / init.vim

Last active December 6, 2019 18:13

vimrc file for use with nvim

	" ============================================================================ "
	" === kcoyner's nvim config === "
	" ============================================================================ "
	" Plugin/package location: ~/.local/share/nvim/site/pack/git-plugins/start

	set runtimepath^=~/.vim runtimepath+=~/.vim/after
	let &packpath = &runtimepath
	let g:python3_host_prog='/usr/local/bin/python3'
	" let g:python_host_prog='/usr/bin/python2'
	" let g:GPGExecutable = 'gpg2 --trust-model auto'

kcoyner / promise_generic.js

Created December 6, 2019 14:35

	function getMoneyBack(money) {
	money = String(money) // force the rejectkk
	return new Promise((resolve, reject) => {
	if (typeof money !== 'number') {
	reject(new Error('money is not a number'))
	} else {
	resolve(money)
	}
	})
	}

kcoyner / callback_generic.js

Last active December 6, 2019 14:55

	function getMoneyBack(money, callback) {
	money = String(money) // force the error
	if (typeof money !== 'number') {
	callback(null, new Error('money is not a number'))
	// callback(new Error('money is not a number'))
	} else {
	callback(money)
	}
	}