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.

npm install fractional-index

or

yarn add fractional-index

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);