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.
34 lines
802 B
34 lines
802 B
3 years ago
|
/**
|
||
|
|
Define a [lazily evaluated](https://en.wikipedia.org/wiki/Lazy_evaluation) property on an object.
|
||
|
|
|
||
|
|
@param object - Object to add property to.
|
||
|
|
@param propertyName - Name of the property to add.
|
||
|
|
@param fn - Called the first time `propertyName` is accessed.
|
||
|
|
|
||
|
|
@example
|
||
|
|
```
|
||
|
|
import defineLazyProp = require('define-lazy-prop');
|
||
|
|
|
||
|
|
const unicorn = {
|
||
|
|
// …
|
||
|
|
};
|
||
|
|
|
||
|
|
defineLazyProp(unicorn, 'rainbow', () => expensiveComputation());
|
||
|
|
|
||
|
|
app.on('user-action', () => {
|
||
|
|
doSomething(unicorn.rainbow);
|
||
|
|
});
|
||
|
|
```
|
||
|
|
*/
|
||
|
|
declare function defineLazyProp<
|
||
|
|
ObjectType extends {[key: string]: unknown},
|
||
|
|
PropertyNameType extends string,
|
||
|
|
PropertyValueType
|
||
|
|
>(
|
||
|
|
object: ObjectType,
|
||
|
|
propertyName: PropertyNameType,
|
||
|
|
fn: () => PropertyValueType
|
||
|
|
): ObjectType & {[K in PropertyNameType]: PropertyValueType};
|
||
|
|
|
||
|
|
export = defineLazyProp;
|