joshwashywash

Zip function for TypeScript

all elements of as must be of type A. all elements of bs must be of type B. you can do this using recursion and you wouldn't have to know about the lengths of the arrays but that's for another gist.

const zip = <A, B>(as: A[], bs: B[]) => {
  const length = Math.min(as.length, bs.length);
  return Array.from({ length }, (_, i) => [as[i], bs[i]]);
};

joshwashywash

Sample an element from an array in TypeScript

const sample = <T>(items: T[]) => items[Math.floor(Math.random() * items.length)];

joshwashywash

Here's how you can know what type item has in the parent component so you get nice autocompletion :)

<script lang="ts">
  type Item = $$Generic;
  export let items: Item[] = [];
</script>

<ul>
 {#each items as item, index}

joshwashywash

Just a higher-order function around fetch.

const createFetch = <T>(fn: (response: Response) => Promise<T>) => {
  return (...params: Parameters<typeof fetch>) => fetch(...params).then(fn);
};

You can use it like this:

joshwashywash

This is named after Ramda's aperture function https://ramdajs.com/docs/#aperture.

const aperture = (n: number) =>
	<T>(xs: T[]): T[][] =>
		n < 1 || n > xs.length
			? []
			: Array.from({ length: xs.length - n + 1 }, (_, i) => xs.slice(i, i + n));