fractional-index

A Javascript implementation of fractional indexes for sorting items, as described originally in: https://observablehq.com/@dgreensp/implementing-fractional-indexing

Given two indexes the library will always return a fractional index at the midpoint between the two. This is particularly useful for realtime collaboration and cases where sending an entire set of ordered items back to the server is undesirable.

Install

npm install fractional-index

or

yarn add fractional-index

Usage

import fractionalIndex from "fractional-index";

const index = fractionalIndex("a", "b");

For start and end of a list pass null as the argument, eg:

import fractionalIndex from "fractional-index";

const index = fractionalIndex("a", null);