bb26

BB26

BB26 is a JavaScript library for working with bijective base-26 (BB26) numbers.

What is bijective base-26 numeration?

You’re probably familiar with BB26 numeration. It’s used for spreadsheet columns, license plate serials, and (probably?) more.

Here’s an example of decimal (base-10) numbers (the numbers you use every day to count things) compared to their corresponding BB26 numbers:

Decimal: | 1 | 2 | 3 | … | 24 | 25 | 26 | 27 | 28 | 29 | …
   BB26: | A | B | C | … |  X |  Y |  Z | AA | AB | AC | …

Install

npm install bb26

API

increment()

function increment(string: string): string;

Increments a bijective base-26 string by one numeral.

import {increment} from 'bb26';

increment('A'); // 'B'
increment('Z'); // 'AA'
increment('AA'); // 'AB'

random()

function random(upper: string): string;
function random(lower: string, upper: string): string;

Produces a random string between the inclusive lower and upper bounds. If only one argument is provided, a string between 'A' and the given string is returned.

import {random} from 'bb26';

random('AAA'); // 'NE'
random('AAA', 'AAAA'); // 'KXZ'

range()

function range(end: string): string[];
function range(start: string, end: string): string[];

Creates an array of bijective base-26 numerals progressing from start up to, but not including, end. If end is not specified, it's set to start with start then set to 'A'.

import {range} from 'bb26';

range('B'); // ['A']
range('C'); // ['A', 'B']
range('B', 'C'); // ['B']
range('B', 'D'); // ['B', 'C']
range('Z', 'AC'); // ['Z', 'AA', 'AB']

toBb26()

function toBb26(number: number): string;

Converts a decimal number to a bijective base-26 string.

import {toBb26} from 'bb26';

toBb26(1); // 'A'
toBb26(2); // 'B'
toBb26(26); // 'Z'
toBb26(27); // 'AA'
toBb26(28); // 'AB'

toDecimal()

function toDecimal(string: string): number;

Converts a bijective base-26 string to a decimal number.

import {toDecimal} from 'bb26';

toDecimal('A'); // 1
toDecimal('B'); // 2
toDecimal('Z'); // 26
toDecimal('AA'); // 27
toDecimal('AB'); // 28

Changelog

5.0.0 – 2025-07-26

Changed

• BREAKING: Require Node.js v20
• Improved performance of random()

Fixed

• Circular imports
• Argument validation in toDecimal()