Ensure a function is only called once
npm install 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.
``sh`
npm install onetime
`js
import onetime from 'onetime';
let index = 0;
const foo = onetime(() => ++index);
foo(); //=> 1
foo(); //=> 1
foo(); //=> 1
onetime.callCount(foo); //=> 3
`
`js
import onetime from 'onetime';
const foo = onetime(() => {}, {throw: true});
foo();
foo();
//=> Error: Function foo can only be called once`
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\false
Default:
Throw an error when called more than once.
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 'onetime';
const foo = onetime(() => {});
foo();
foo();
foo();
console.log(onetime.callCount(foo));
//=> 3
`
#### fn
Type: Function`
The function to get call count from.