lazy-val

What is lazy-val?

The lazy-val npm package provides a way to lazily evaluate values. This means that the value is only computed when it is needed, which can help improve performance and reduce unnecessary computations.

What are lazy-val's main functionalities?

Lazy Value Initialization

This feature allows you to define a value that is only computed when it is first accessed. Subsequent accesses to the value will return the cached result without recomputing it.

const { Lazy } = require('lazy-val');

const lazyValue = new Lazy(() => {
  console.log('Computing the value...');
  return 42;
});

console.log('Before accessing the value');
console.log(lazyValue.value); // Logs 'Computing the value...' and then '42'
console.log('After accessing the value');
console.log(lazyValue.value); // Logs '42' without recomputing

Resetting the Lazy Value

This feature allows you to reset the lazy value, forcing it to recompute the next time it is accessed.

const { Lazy } = require('lazy-val');

const lazyValue = new Lazy(() => {
  console.log('Computing the value...');
  return Math.random();
});

console.log(lazyValue.value); // Computes and logs the value
lazyValue.reset();
console.log(lazyValue.value); // Recomputes and logs the new value

Other packages similar to lazy-val

lazy.js

lazy.js is a utility library that provides lazy evaluation for JavaScript. It offers a wide range of functionalities for working with collections and sequences in a lazy manner. Compared to lazy-val, lazy.js is more feature-rich and provides more utilities for working with data.

lodash

lodash is a popular utility library that provides a wide range of functions for working with arrays, objects, and other data types. It includes a `_.memoize` function that can be used to achieve similar lazy evaluation for functions. While lodash is more general-purpose, lazy-val is more focused on lazy value initialization.

memoizee

memoizee is a library specifically designed for memoization, which is a form of lazy evaluation where the result of a function call is cached based on its arguments. It provides more advanced memoization features compared to lazy-val, such as cache expiration and custom cache resolvers.

README

lazy-val

Lazy value.

class Lazy<T> {
    constructor(creator: () => Promise<T>)
    readonly hasValue: boolean
    value: Promise<T>
}