singulure

A tiny JavaScript utility to ensure a function can only be called a single time — forever.

Why singulure?

singulure is a lightweight, modern JavaScript utility that guarantees a function can be invoked only once, ever. Perfect for initialization routines, event guards, or any scenario where you want to prevent repeated calls.

Written as an ES module with zero dependencies, singulure is minimal, performant, and straightforward to use both in frontend and backend projects.

Installation

npm install singulure

Usage

import { singulure } from 'singulure';

const initialize = singulure(() => {
  console.log('Initialized!');
});

initialize(); // Logs "Initialized!"
initialize(); // Does nothing on subsequent calls

API

singulure(fn: Function): Function

Wraps the function fn so it can only be called once. All future calls return the cached result from the first call.

• fn — The function to wrap.
• Returns — A new function that invokes fn once and then always returns the first result.

Testing

Run the test suite with:

npm test

Make sure you have a test.js file in the project root.

License

MIT © Geoffrey Callaghan

Sponsorship

This project is proudly sponsored by FabForm.io — build amazing forms effortlessly.