Tommy Hodgins tomhodgins

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

	function $(container, selector) {
	const els =
	typeof selector === 'string'
	? container.querySelectorAll(selector)
	: typeof container === 'string' ? document.querySelectorAll(container) : [container];

	const fns = {
	removeClass(...cls) {
	els.forEach(el => {
	el.classList.remove(...cls);

	const Range = (a, b) => Array.from({ length: b - a }, (_, i) => a + i)
	const NumTest = (n, text) => k => !(k % n) ? text : ''
	const Tests = data => Object.entries(data).map(([n, text]) => NumTest(n, text))
	const RangeTest = tests => n => tests.map(fn => fn(n)).join('') \|\| n
	const RangeMap = (a, b, tests) => Range(a, b).map(RangeTest(tests))
	const fizzBuzz = (a, b) => RangeMap(a, b, Tests({
	5: 'Fizz',
	3: 'Buzz',
	}))

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	const random = (min, max) => Math.random() * (max - min) + min;
	return (callback, min, max) => {
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	start: performance.now(),
	total: random(min, max)
	};
	const tick = now => {
	if (time.total <= now - time.start) {
	time.start = now;

	import re, sys # this file requires python 3
	def parse(tokens):
	stack = ([], None)
	for t in tokens:
	if t == '(':
	stack = ([], stack)
	elif t == ')':
	(finished_list, stack) = stack
	stack[0].append(finished_list)
	elif not t.startswith(';;'):

	(datatype is-prime
	if (is-prime? N)
	N : number;
	==============
	N : prime;)

	(define is-prime?
	X -> (prime* X (/ X 2) 2) where (number? X)
	_ -> false)

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	/* Every css property should have its default value */
	aspect-ratio: intrinsic;
	/* same as */
	aspect-ratio: initial;
	}

	/**
	* Keyword `intrinsic` tells brower to try to get the ratio
	* from the element itself.

	$(window).resize(function(){
	function sameHeight(container, child) {
	$(container).each(function(){
	var tallest = 0;
	$(child, this).each(function(){
	if($(this).height() > tallest) {
	tallest = $(this).height();
	}
	});
	$(child, this).height(tallest);