custom-ts-utils

Small, zero-dependency TypeScript utility library.

• ESM-first package
• Immutable behavior (returns new values, does not mutate input)
• Safe for null / undefined inputs in utility functions

Install

npm i custom-ts-utils

Quick usage

import {
	map,
	filter,
	reduce,
	reduceRight,
	some,
	every,
	find,
	pluck,
	lens,
	view,
	set,
} from "custom-ts-utils";

const nums = [1, 2, 3, 4];

const doubled = map((n) => n * 2, nums);                // [2, 4, 6, 8]
const evens = filter((n) => n % 2 === 0, nums);         // [2, 4]
const total = reduce((acc, n) => acc + n, 0, nums);     // 10
const totalRight = reduceRight((acc, n) => acc + n, 0, nums); // 10
const hasBig = some((n) => n > 3, nums);                // true
const allPositive = every((n) => n > 0, nums);          // true

Functions

map(transform, array)

Transforms each item and returns a new array.

filter(predicate, array)

Returns a new array with items that match the predicate.

reduce(reducer, initialValue, array)

Reduces items left-to-right into one value.

reduceRight(reducer, initialValue, array)

Reduces items right-to-left into one value.

some(predicate, array)

Returns true if at least one item matches.

every(predicate, array)

Returns true if all items match.

find(array, predicate)

Finds first item matching a predicate.

find(array, key, value)

Finds first item where item[key] === value.

const users = [
	{ id: 1, name: "A" },
	{ id: 2, name: "B" },
];

find(users, (u) => u.id === 2);   // { id: 2, name: "B" }
find(users, "name", "A");      // { id: 1, name: "A" }

pluck(keyOrPathOrKeys, array)

Extract values from objects by:

• single key: "name"
• deep path: "address.city"
• multiple keys: ["id", "name"]

const rows = [
	{ id: 1, name: "A", address: { city: "Chennai" } },
	{ id: 2, name: "B", address: { city: "hyd } },
];

pluck("name", rows);            // ["A", "B"]
pluck("address.city", rows);    // ["Chennai", "hyd"]
pluck(["id", "name"], rows);  // [{ id: 1, name: "A" }, { id: 2, name: "B" }]

Lens utilities: lens(path), view(lens, obj), set(lens, value, obj)

Simple immutable nested read/write helpers.

const user = { profile: { name: "pugal" } };
const nameLens = lens("profile.name");

view(nameLens, user); // "livi"

const updated = set(nameLens, "harish", user);
// updated => { profile: { name: "harish" } }
// user is unchanged

Notes

• Package format: ESM only
• Type declarations included