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readme.md |
readme.md
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
.
Install
$ npm install onetime
Usage
import onetime from 'onetime';
let index = 0;
const foo = onetime(() => ++index);
foo(); //=> 1
foo(); //=> 1
foo(); //=> 1
onetime.callCount(foo); //=> 3
import onetime from 'onetime';
const foo = onetime(() => {}, {throw: true});
foo();
foo();
//=> Error: Function `foo` can only be called once
API
onetime(fn, options?)
Returns a function that only calls fn
once.
fn
Type: Function
Function that should only be called once.
options
Type: object
throw
Type: boolean
Default: false
Throw an error when called more than once.
onetime.callCount(fn)
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
.
import onetime from 'onetime';
const foo = onetime(() => {});
foo();
foo();
foo();
console.log(onetime.callCount(foo));
//=> 3
fn
Type: Function
Function to get call count from.
onetime for enterprise
Available as part of the Tidelift Subscription.
The maintainers of onetime and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source dependencies you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact dependencies you use. Learn more.