https://github.com/sindresorhus/p-lazy

Create a lazy promise that defers execution until it's awaited or when .then() or .catch() is called
https://github.com/sindresorhus/p-lazy

Last synced: about 2 months ago
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Create a lazy promise that defers execution until it's awaited or when .then() or .catch() is called

• Host: GitHub
• URL: https://github.com/sindresorhus/p-lazy
• Owner: sindresorhus
• License: mit
• Created: 2016-11-07T09:05:39.000Z (over 7 years ago)
• Default Branch: main
• Last Pushed: 2022-07-09T03:22:46.000Z (almost 2 years ago)
• Last Synced: 2024-04-12T20:29:32.593Z (3 months ago)
• Language: JavaScript
• Homepage:
• Size: 17.6 KB
• Stars: 263
• Watchers: 8
• Forks: 10
• Open Issues: 0
• Metadata Files:
  • Readme: readme.md
  • Funding: .github/funding.yml
  • License: license
  • Security: .github/security.md

Lists

• awesome-promises - p-lazy - Create a lazy promise that defers execution until `.then()` or `.catch()` is called (Convenience Utilities / sindresorhus's many Promise utilities ([see notes](https://github.com/sindresorhus/promise-fun)))
• promise-fun - p-lazy
• awesome-stars - p-lazy

README

        
# p-lazy

> Create a lazy promise that defers execution until it's awaited or when `.then()` or `.catch()` is called

Useful if you're doing some heavy operations and would like to only do it when the promise is actually used.

## Install

```sh

npm install p-lazy

```

## Usage

```js

import PLazy from 'p-lazy';

const lazyPromise = new PLazy(resolve => {

	someHeavyOperation(resolve);

});

// `someHeavyOperation` is not yet called

await doSomethingFun;

// `someHeavyOperation` is called

console.log(await lazyPromise);

```

## API

### new PLazy(executor)

Same as the [`Promise` constructor](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Promise). `PLazy` is a subclass of `Promise`.

### PLazy.from(fn)

Create a `PLazy` promise from a promise-returning or async function.

### PLazy.resolve(value)

Create a `PLazy` promise that is resolved with the given `value`, or the promise passed as `value`.

### PLazy.reject(reason)

Create a `PLazy` promise that is rejected with the given `reason`.

## Related

- [p-cancelable](https://github.com/sindresorhus/p-cancelable) - Create a promise that can be canceled

- [p-defer](https://github.com/sindresorhus/p-defer) - Create a deferred promise

- [lazy-value](https://github.com/sindresorhus/lazy-value) - Create a lazily evaluated value

- [define-lazy-prop](https://github.com/sindresorhus/define-lazy-prop) - Define a lazily evaluated property on an object

- [More…](https://github.com/sindresorhus/promise-fun)