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Awesome Open Source


Ultra Tiny, Opinionated Positioning Engine

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NanoPop is an ultra-tiny positioning engine. Hold up, isn't there PopperJS? Yeah - and PopperJS is great! But there are tons of features that, in most cases, you just might not need. This library is less than a third of PopperJS.

When should I use Nanopop and not PopperJS?

  1. Situations where you want full control over positioning, including handling events such as scrolling, and manual resizing.
  2. Performance-critical cases with lots of elements [...] nanopop will only makes changes if you say so.
  3. Poppers with minimal footprint such as drop-downs and tooltips which don't require that much configurability.
  4. You might have some special needs about how your popper behaves. NanoPop exposes a function for the sole purpose of positioning something, use it in your own library!

This library was originally part of pickr - now ported to TS with tests and a few updates / bug-fixes.

Heads up! This is the readme for v2 - if you're looking for the first version head over here (v1 is not maintained anymore).

Getting Started

Install via npm:

$ npm install nanopop

Install via yarn:

$ yarn add nanopop

Include directly via jsdelivr:

<script src="[email protected]/lib/nanopop.min.js"></script>

Using JavaScript Modules:

import {
    reposition,   // Core, stateless function to reposition an element
    createPopper, // Stateful function which keeps track of your configuration
    defaults,     // A subset of nanopops options used as default values
    version       // Current version
} from ''

🌟 NanoPop is fully tree-shakable! E.g. if you only use reposition you'll probably end up with less than 500B code!


    /* reference: */ document.querySelector('.btn'),
    /* popper: */ document.querySelector('.dropdown'),
    /* We're using the default options */

⚠ The popper-element must have set position to fixed.

ℹ Because the default-container is document.documentElement you might have to increase the height of the html element to make room for your popper (e.g. html {height: 100vh;})

All options

import {reposition, createPopper} from 'nanopop';

// Using a object and reposition directly
const nanopop = reposition(reference, popper, {

    // The DOMRect of the container, it used the html-element as default.
    // You could also create your own boundary using a custon DOMRect (!
    container: document.documentElement.getBoundingClientRect(),

    // Margin between the popper element and the reference
    margin: 8,

    // Preferred position, any combination of [top|right|bottom|left]-[start|middle|end] is valid.
    // 'middle' is used as default-variant if you leave it out.
    position: 'bottom-middle',

    // In case the variant-part (start, middle or end) cannot be applied you can specify what (and if)
    // should be tried next.
    variantFlipOrder: {
        start: 'sme', // In case of -start try 'start' first, if that fails 'middle' and 'end' if both doesn't work.
        middle: 'mse',
        end: 'ems'

    // The same as variantFlipOrder, but if all variants fail you might want to try other positions.
    positionFlipOrder: {
        top: 'tbrl', // Try 'top' first, 'bottom' second, 'right' third and 'left' as latest position.
        right: 'rltb',
        bottom: 'btrl',
        left: 'lrbt'

 * Using the createPopper function to create a stateful wrapper
 * Correct ways of calling it are:
 * createPopper(reference: HTMLElement, popper: HTMLElement, options?: NanoPopOptions)
 * createPopper(options?: NanoPopOptions)
 * ⚠ If you omit options entierly you'll have to set both the reference and the popper later when calling .update!
const popper = createPopper({...});
popper.update(); // You can pass an object to update which will get merged with the existing config.

Calling popper.update(...) or reposition(...) both returns a position-pair (For example te for Top-End) or null based on if it was possible to find a position for the popper without clipping it._

Tip: The returned position-pair is perfect for tool-tips to give them a little arrow!


  1. The popper-element must have position set to fixed.
  2. If nanopop cannot find a position without clipping your popper it'll revert its top and left values - you can use css / js to handle this case.

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