onetime
v7.0.0
Published
Ensure a function is only called once
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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
The 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
The function to get call count from.