Darren Semotiuk DarrenSem

## array_iteration_thoughts.md

      
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                ljharb
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              February 14, 2026 23:20
            
              
                Array iteration methods summarized
              
          
    Array Iteration

https://gist.github.com/ljharb/58faf1cfcb4e6808f74aae4ef7944cff
While attempting to explain JavaScript's reduce method on arrays, conceptually, I came up with the following - hopefully it's helpful; happy to tweak it if anyone has suggestions.
Intro

JavaScript Arrays have lots of built in methods on their prototype. Some of them mutate - ie, they change the underlying array in-place. Luckily, most of them do not - they instead return an entirely distinct array. Since arrays are conceptually a contiguous list of items, it helps code clarity and maintainability a lot to be able to operate on them in a "functional" way. (I'll also insist on referring to an array as a "list" - although in some languages, List is a native data type, in JS and this post, I'm referring to the concept. Everywhere I use the word "list" you can assume I'm talking about a JS Array) This means, to perform a single operation on the list as a whole ("atomically"), and to return a new list - thus making it mu

  
## bash-cheatsheet.sh
#!/bin/bash
#####################################################
# Name: Bash CheatSheet for Mac OSX
#
# A little overlook of the Bash basics
#
# Usage:
#
# Author: J. Le Coupanec
# Date: 2014/11/04

## codility_solutions.txt
Lesson 1 - Iterations
- BinaryGap - https://codility.com/demo/results/trainingU2FQPQ-7Y4/

Lesson 2 - Arrays
- OddOccurrencesInArray - https://codility.com/demo/results/trainingFN5RVT-XQ4/
- CyclicRotation - https://codility.com/demo/results/trainingSH2W5R-RP5/

Lesson 3 - Time Complexity
- FrogJmp - https://codility.com/demo/results/training6KKWUD-BXJ/
- PermMissingElem - https://codility.com/demo/results/training58W4YJ-VHA/

## regular-expressions.cheatsheet.coffee
# SYNTAX:

var pattern = new RegExp(pattern, attributes);  # attributes: g (global); i (case-sensitive); m (multiline matches)
var pattern = /pattern/attributes;  # same as above


# BRACKETS:

[...]: Any one character between the brackets.
[^...]: Any one character not between the brackets.

## 1-npm-cheatsheet-command-lines.sh
# NPM CheatSheet.
# Super easy intall: npm comes with node now.
# To create your own npm package: https://www.npmjs.org/doc/misc/npm-developers.html
# More: https://www.npmjs.org/doc/


# 1. NPM Command Lines.
# Local mode is the default.
# Use --global or -g on any command to operate in global mode instead.

## index.html
<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8" />
    <title>Add React in One Minute</title>
  </head>
  <body>

    <h2>Add React in One Minute</h2>
    <p>This page demonstrates using React with no build tooling.</p>

## MarkDownLivePreview.com-resizer.js
//// Update: Go here instead, works as a Bookmarklet or as an included file via <script src="...">. (I also added a printButton.js)
//// https://github.com/DarrenSem/markdown/blob/master/static/resizer.js

// MarkDownLivePreview.com-resizer.js -- bookmarklet to add 'Toggle Editor' (and also width-resizer) - instead of waiting for repo update that might use something like this <script src="./static/resizer.js"></script>
// (09Sep2025 938am) 2209 char  javascript:void function(){"use strict";const e="minedit",t="extra-button",i="mouse",n="width",r=document,o=e=>r.getElementById(e),s=(e,t)=>Object.assign(r.createElement(e||"div"),t),d=(e,...t)=>e.addEventListener(...t),l=(e,...t)=>e.removeEventListener(...t),a=e=>e.preventDefault(),c=setTimeout,g=40,m=window,f=(e="resizer-css")=>{if(o(e))return;const i=["\nbody {\n  margin: 0;\n  height: 100vh;\n  overflow: hidden;\n}\n#container {\n  display: flex;\n  width: 100%;\n  height: 100%;\n  overflow: hidden;\n}\n#resizer {\n  width: 4px;\n  background-color: green;\n

## following.py
import requests, re, sys

url = "https://mobile.twitter.com/{}/following"
cursor = ""
usernames = []
first = True

if len(sys.argv) < 2:
    print("Usage: python followers.py <username>")
    quit(1)

## width.js
// width.js - Bookmarklet for OpenAI playground to fix maxWidth of "Configure" panel (due to latest layout update); add as browser Favorite then click to toggle visibility
// https://gist.github.com/DarrenSem/0d9da09fc5a7b95abcc0df95d65b02c7


// 05Apr2025 234pm: will now FIRST close "Configure" if already opened as slide-in panel version (could have BOTH versions visible!)
// 2016 char  javascript:void function(){const a=null,b="innerText",c=(b,c=1)=>{let d=b;for(;c--&&(d=d?.parentElement););return d||a},d=(a,b)=>a.test(b??""),e=()=>{const a=document.querySelectorAll("button > span > span + span.sr-only"),c=Array.from(a).filter((a,c)=>{const e=a[b],f=d(/Configure/,e);return console.log({isTextConfigure:f,text:e,el:a,i:c}),f});return console.log({collConfigureButtons:c,collButtonSpans:a,selButtonSpans:"button > span > span + span.sr-only"}),c},f=e=>{let f,g,h=a;const i=c(e,1),j=i.querySelectorAll("button");for(f of j)if(g=f.dataset,console.log({dataset:g,elButton:f}),!d(/\S/,f[b])&&"secondary"==g?.color&&"md"

## above(parentElement).js + next(siblingElement).js
// above.js (PARENT element, levels = #) + next.js (SIBLING element, levels = #) helper functions instead of foo.parentElement.parentElement.parentElement etc.

// https://gist.github.com/DarrenSem/4d37711fb71a484b6ed2356c60e3c94a


// PARENT element: ...
const above = (startingElement, levels = 1) => {
  let el = startingElement;
  while ( levels-- && (el = el?.parentElement) );
  return el || null;
	#!/bin/bash
	#####################################################
	# Name: Bash CheatSheet for Mac OSX
	#
	# A little overlook of the Bash basics
	#
	# Usage:
	#
	# Author: J. Le Coupanec
	# Date: 2014/11/04
	Lesson 1 - Iterations
	- BinaryGap - https://codility.com/demo/results/trainingU2FQPQ-7Y4/

	Lesson 2 - Arrays
	- OddOccurrencesInArray - https://codility.com/demo/results/trainingFN5RVT-XQ4/
	- CyclicRotation - https://codility.com/demo/results/trainingSH2W5R-RP5/

	Lesson 3 - Time Complexity
	- FrogJmp - https://codility.com/demo/results/training6KKWUD-BXJ/
	- PermMissingElem - https://codility.com/demo/results/training58W4YJ-VHA/
	# SYNTAX:

	var pattern = new RegExp(pattern, attributes); # attributes: g (global); i (case-sensitive); m (multiline matches)
	var pattern = /pattern/attributes; # same as above


	# BRACKETS:

	[...]: Any one character between the brackets.
	[^...]: Any one character not between the brackets.
	# NPM CheatSheet.
	# Super easy intall: npm comes with node now.
	# To create your own npm package: https://www.npmjs.org/doc/misc/npm-developers.html
	# More: https://www.npmjs.org/doc/


	# 1. NPM Command Lines.
	# Local mode is the default.
	# Use --global or -g on any command to operate in global mode instead.
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="UTF-8" />
	<title>Add React in One Minute</title>
	</head>
	<body>

	<h2>Add React in One Minute</h2>
	<p>This page demonstrates using React with no build tooling.</p>
	//// Update: Go here instead, works as a Bookmarklet or as an included file via <script src="...">. (I also added a printButton.js)
	//// https://github.com/DarrenSem/markdown/blob/master/static/resizer.js

	// MarkDownLivePreview.com-resizer.js -- bookmarklet to add 'Toggle Editor' (and also width-resizer) - instead of waiting for repo update that might use something like this <script src="./static/resizer.js"></script>
	// (09Sep2025 938am) 2209 char javascript:void function(){"use strict";const e="minedit",t="extra-button",i="mouse",n="width",r=document,o=e=>r.getElementById(e),s=(e,t)=>Object.assign(r.createElement(e\|\|"div"),t),d=(e,...t)=>e.addEventListener(...t),l=(e,...t)=>e.removeEventListener(...t),a=e=>e.preventDefault(),c=setTimeout,g=40,m=window,f=(e="resizer-css")=>{if(o(e))return;const i=["\nbody {\n margin: 0;\n height: 100vh;\n overflow: hidden;\n}\n#container {\n display: flex;\n width: 100%;\n height: 100%;\n overflow: hidden;\n}\n#resizer {\n width: 4px;\n background-color: green;\n
	import requests, re, sys

	url = "https://mobile.twitter.com/{}/following"
	cursor = ""
	usernames = []
	first = True

	if len(sys.argv) < 2:
	print("Usage: python followers.py <username>")
	quit(1)
	// width.js - Bookmarklet for OpenAI playground to fix maxWidth of "Configure" panel (due to latest layout update); add as browser Favorite then click to toggle visibility
	// https://gist.github.com/DarrenSem/0d9da09fc5a7b95abcc0df95d65b02c7


	// 05Apr2025 234pm: will now FIRST close "Configure" if already opened as slide-in panel version (could have BOTH versions visible!)
	// 2016 char javascript:void function(){const a=null,b="innerText",c=(b,c=1)=>{let d=b;for(;c--&&(d=d?.parentElement););return d\|\|a},d=(a,b)=>a.test(b??""),e=()=>{const a=document.querySelectorAll("button > span > span + span.sr-only"),c=Array.from(a).filter((a,c)=>{const e=a[b],f=d(/Configure/,e);return console.log({isTextConfigure:f,text:e,el:a,i:c}),f});return console.log({collConfigureButtons:c,collButtonSpans:a,selButtonSpans:"button > span > span + span.sr-only"}),c},f=e=>{let f,g,h=a;const i=c(e,1),j=i.querySelectorAll("button");for(f of j)if(g=f.dataset,console.log({dataset:g,elButton:f}),!d(/\S/,f[b])&&"secondary"==g?.color&&"md"
	// above.js (PARENT element, levels = #) + next.js (SIBLING element, levels = #) helper functions instead of foo.parentElement.parentElement.parentElement etc.

	// https://gist.github.com/DarrenSem/4d37711fb71a484b6ed2356c60e3c94a


	// PARENT element: ...
	const above = (startingElement, levels = 1) => {
	let el = startingElement;
	while ( levels-- && (el = el?.parentElement) );
	return el \|\| null;