You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
64 lines
1.3 KiB
64 lines
1.3 KiB
# define-lazy-prop [](https://travis-ci.org/sindresorhus/define-lazy-prop) |
|
|
|
> Define a [lazily evaluated](https://en.wikipedia.org/wiki/Lazy_evaluation) property on an object |
|
|
|
Useful when the value of a property is expensive to generate, so you want to delay the computation until the property is needed. For example, improving startup performance by deferring nonessential operations. |
|
|
|
|
|
## Install |
|
|
|
``` |
|
$ npm install define-lazy-prop |
|
``` |
|
|
|
|
|
## Usage |
|
|
|
```js |
|
const defineLazyProp = require('define-lazy-prop'); |
|
|
|
const unicorn = { |
|
// … |
|
}; |
|
|
|
defineLazyProp(unicorn, 'rainbow', () => expensiveComputation()); |
|
|
|
app.on('user-action', () => { |
|
doSomething(unicorn.rainbow); |
|
}); |
|
``` |
|
|
|
|
|
## API |
|
|
|
### defineLazyProp(object, propertyName, fn) |
|
|
|
#### object |
|
|
|
Type: `Object` |
|
|
|
Object to add property to. |
|
|
|
#### propertyName |
|
|
|
Type: `string` |
|
|
|
Name of the property to add. |
|
|
|
#### fn |
|
|
|
Type: `Function` |
|
|
|
Called the first time `propertyName` is accessed. Expected to return a value. |
|
|
|
|
|
## Related |
|
|
|
- [lazy-value](https://github.com/sindresorhus/lazy-value) - Create a lazily evaluated value |
|
- [import-lazy](https://github.com/sindresorhus/import-lazy) - Import a module lazily |
|
- [p-lazy](https://github.com/sindresorhus/p-lazy) - Create a lazy promise |
|
|
|
|
|
## License |
|
|
|
MIT © [Sindre Sorhus](https://sindresorhus.com)
|
|
|