@elgato/utils

Utilities used throughout the Elgato ecosystem.

Installation

npm install @elgato/utils

Disposables

deferredDisposable

Creates a new function that implements Symbol.dispose and accepts a disposer function. The disposer function is called when the new function is disposed.

import { deferredDisposable } from "@elgato/utils";

{
    using deferredDisposable(() => console.log("Hello world"));
    // ...
}

// "Hello world"

DisposableStack

Stack of managed resources, controlled by a single disposer. Partial polyfill of TC39 Explicit Resource Management's DisposableStack.

import { DisposableStack } from "@elgato/utils";

{
    using stack = new DisposableStack();
    stack.defer(() => "Hello");
    stack.defer(() => "world");
    // ...
}

// "Hello"
// "world"

Events

EventEmitter

An strongly-typed event emitter that enables the listening for, and emitting of, events; supported in browser and Node.js environments.

import { EventEmitter } from "@elgato/utils";

type EventMap = {
    created: [name: string];
};

const emitter = new EventEmitter<EventMap>();
emitter.on("created", (name: string) => {
    // ...
});

JSON

JsonObject

Type that represents an object within JSON.

import { type JsonObject } from "@elgato/utils";

const obj: JsonObject = {
    name: "Elgato",
};

JsonPrimitive

Type that represents a primitive within JSON, for example a string or number.

import { type JsonPrimitive } from "@elgato/utils";

const value: JsonPrimitive = "Elgato";

JsonValue

Type that represents a valid JSON value, for example an object, array, or primitive.

import { type JsonValue } from "@elgato/utils";

const value: JsonValue = ["Hello", "World"];

Miscellaneous

Enumerable

Provides a read-only iterable collection of items that also acts as a partial polyfill for iterator helpers.

import { Enumerable } from "@elgato/utils";

const items = new Enumerable(["One", "Two", "Three", "Four"]);
items
    .drop(1) // Drop "One"
    .take(2); // Take "Two" & "Three"

Polyfilled iterator helpers:

• Symbol.iterator
• asIndexedPairs()
• drop(limit)
• every(predicate)
• filter(predicate)
• find(predicate)
• findLast(predicate)
• flapMap(mapper)
• forEach(fn)
• includes(search)
• map(mapper)
• reduce(accumulator, initial)
• some(predicate)
• take(limit)
• toArray()

Lazy

Object that wraps a lazily instantiated value, similar to C# Lazy<T>.

import { Lazy } from "@elgato/utils";

const lazy = new Lazy(() => "Hello world");
lazy.value; // "Hello world";

Objects

get(source, path)

Gets the value at the specified (deep) path.

import { get } from "@elgato/utils";

const obj = {
    name: "Elgato",
};

get(obj, "name"); // Elgato

set(target, path, value)

Sets the value at the specified (deep) path.

import { get } from "@elgato/utils";

const obj = {
    name: "Gato",
};

set(obj, "name", "Elgato"); // { name: "Elgato" }

Parsers

parseBoolean(value)

Parses the value a truthy-boolean; the strings "0" and "false" are parsed as false.

import { parseBoolean } from "@elgato/utils";

const a = parseBoolean(1); // true
const b = parseBoolean("false"); // false

parseNumber(value)

Attempts to parse a value to a number; returns undefined when parsing was unsuccessful.

import { parseNumber } from "@elgato/utils";

const number = parseNumber("13"); // 13

Promises

withResolvers()

Function that returns an object that contains the promise, and two functions to resolve or reject it. Polyfill of Promise.withResolvers().

import { withResolvers } "@elgato/utils";

const { promise, resolve, reject } = withResolvers<string>();

Strings

format(format, ...args)

Formats the specified string, replacing placeholders with their associated arguments.

import { format } from "@elgato/utils";

format("Hello {0}, from {1}", "world", "Elgato"); // Hello world, from Elgato

Timers

debounce(fn, delay)

Wraps a function; subsequent invocations of the wrapped function made within the specified delay are debounced to prevent multiple calls.

import { debounce } from "@elgato/utils";

const fn = debounce(() => console.log("Hello world"), 1000);

fn(); // Debounced
fn(); // "Hello world"