Lazy (javascript version)

Table of content

• Installation
• Usage
  • Lazy value
  • Non-lazy value
  • Specialized non-lazy value
  • Common lazy
• Contribution

This project is an implementation based on the Kotlin Lazy. All of this with additional features to help the reusing of some values.

Installation

npm install @joookiwi/lazy
npm i @joookiwi/lazy

npm install --save @joookiwi/lazy
npm i -S @joookiwi/lazy

npm install --save-dev @joookiwi/lazy
npm i -D @joookiwi/lazy

Usage

The usage is similar to the kotlin usage like val value by lazy { someValue } in kotlin as well as the non-lazy implementation like val value = lazyOf(someValue).

But since there is no significant dependency toward this specifically. Here is an implementation of the lazy via 2 functions

• lazy to load the value later
• lazyOf to have a Lazy but with an already loaded value

Lazy value

Using the lazy value will always return a Lazy object holding a value.

import {lazy} from "@joookiwi/lazy"

const firstValue = lazy(() => 2)
firstValue.isInitialized // false
firstValue.value         // 2
firstValue.isInitialized // true

Non-lazy value

If the value is already known, then just use lazyOf() in order to have a Lazy with an already loaded value.

import {lazyOf} from "@joookiwi/lazy"

const firstValue = lazyOf(2)
firstValue.isInitialized // true
firstValue.value         // 2
firstValue.isInitialized // true

Specialized non-lazy value

There are some specialized lazyOf()-like Lazy to reuse the CommonLazy values depending on what it has received:

• booleanLazyOf for the boolean
• numberLazyOf for the number
• bigintLazyOf for the bigint
• dateLazyOf for the Date

Common lazy

When using the lazy methods, it always creates a new instance.

But, there could be some cases where an already known value is there.

Here is the full list of the common Lazy instances:

| Value | With string | With character | With BigInt | |-----------------------------------------------------|:------------|:---------------|:------------| | null | yes | | | | undefined | yes | | | | true / false | yes | | | | -1 / 0 / 1 / 2 | yes | yes | yes | | NaN / ∞ (infinity) / -∞ (-infinity) | yes | | | | ln(2) / ln(10) | | | | | log₂(E) / log₁₀(E) | | | | | E, π (pi), τ (tau) | | | | | / \t / \n | | yes | | | epoch date | | | | | invalid date | yes | | | | empty String → '' | | | | | empty object → Readonly<{}> | | | | | empty Array → readonly [] | | | | | empty Set → ReadonlySet<never> | | | | | empty WeakSet → Readonly<WeakSet<WeakKey>> | | | | | empty Map → ReadonlyMap<unknown, never> | | | | | empty WeakMap → Readonly<WeakMap<WeakKey, never>> | | | |

Contribution

You can contribute to great simple packages. All with similar behaviour across different languages (like Java, Kotlin, C# and PHP). It can be done 2 different ways:

• GitHub sponsor or
•