@tkesgar/lazy
v1.1.0
Published
Run a function lazily
Downloads
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Readme
lazy
Run a function lazily
Installation
$ npm install @tkesgar/lazy
Usage
function doSomething() {
process.nextTick(() => {
console.log('yo')
})
return Math.random()
}
const myLazy = new Lazy(doSomething)
console.log(myLazy.value)
console.log(myLazy.value)
console.log(myLazy.value)
// 0.7474503288311625
// 0.7474503288311625
// 0.7474503288311625
// yo
async function doSomethingAsync() {
await new Promise(resolve => process.nextTick(() => {
console.log('yo')
resolve()
})))
return Math.random()
}
const myLazyAsync = new LazyAsync(doSomethingAsync)
console.log(await myLazyAsync.getValue())
console.log(await myLazyAsync.getValue())
console.log(await myLazyAsync.getValue())
// yo
// 0.22380571408704864
// 0.22380571408704864
// 0.22380571408704864
console.log(myLazyAsync.value)
// 0.22380571408704864
const lazyDoSomething = lazify(doSomething)
lazyDoSomething()
lazyDoSomething()
lazyDoSomething()
// 0.43478154082214004
// yo
// 0.43478154082214004
// 0.43478154082214004
const lazyDoSomethingAsync = lazifyAsync(doSomethingAsync)
await lazyDoSomethingAsync()
await lazyDoSomethingAsync()
await lazyDoSomethingAsync()
// yo
// 0.5468407710930714
// 0.5468407710930714
// 0.5468407710930714
Recipes
Lazy initialization
// database.ts
export const db = knex({
client: "postgres",
connection: getConnectionConfig(),
})
)
A database connection will always be created, even if it is not used.
// database.ts
const _db = new Lazy(() =>
knex({
client: "postgres",
connection: getConnectionConfig(),
})
);
export function db(): LazyValueOf<typeof _db> {
return _db.value;
}
The database connection will never be created if the script does not call
db()
.
License
Licensed under MIT License.