Ensure a function is only called once. Forked from sindresorhus/onetime, with native TypeScript support.
npm install @reedchan/onetime> Ensure a function is only called once
When called multiple times it will return the return value from the first call.
Unlike the module once, this one isn't naughty and extending Function.prototype.
This package is a lightweight fork of sindresorhus/onetime that preserves the original behavior and keeps the public API fully compatible, while additionally providing:
- CommonJS support out of the box
- Native TypeScript typings (no separate install)
- Zero runtime dependencies
``shpnpm (recommended)
pnpm add @reedchan/onetime
Features
- 🚀 100% API-compatible with the original
onetime package
- ⭐ Supports both ESM and CommonJS consumers
- 🔥 Native TypeScript support via included types field
- 🎉 Zero runtime dependenciesUsage
`typescript
import onetime from '@reedchan/onetime';let index = 0;
const foo = onetime(() => ++index);
foo(); //=> 1
foo(); //=> 1
foo(); //=> 1
onetime.callCount(foo); //=> 3
``typescript
import onetime from '@reedchan/onetime';const foo = onetime(() => {}, {throw: true});
foo();
foo();
//=> Error: Function
foo can only be called once
`API
$3
Returns a function that only calls
fn once.#### fn
Type:
FunctionThe function that should only be called once.
#### options
Type:
object##### throw
Type:
boolean\
Default: falseThrow an error when called more than once.
$3
Returns a number representing how many times
fn has been called.Note: It throws an error if you pass in a function that is not wrapped by
onetime.`js
import onetime from '@reedchan/onetime';const foo = onetime(() => {});
foo();
foo();
foo();
console.log(onetime.callCount(foo));
//=> 3
`#### fn
Type:
Function`The function to get call count from.