numerology

converts a string to a number in the given range

Installation | Examples | Annotated source | License

Installation

npm install numerology

Examples

Name to port number

Convert a name to a port number, deterministically

const numerology = require('numerology')

const userPortsRange = [1024, 49151]
const port = numerology('my-app-name', userPortsRange)

Distribute domains

Suppose you have a list of domains you want to distribute in 6 folders, in a random but balanced way. You can associate a number from 1 to 6 with the snippet numerology(domain, [1, 7]), launch the following command to get the result.

node examples/distributeDomains.js | sort | uniq -c
 148 folder1
 148 folder2
 139 folder3
 138 folder4
 146 folder5
 153 folder6
 128 folder7

Annotated source

Latin alphabet system numerology, which actually is not implemented by this package, assigns a number to every lower case latin letter. The function below uses String.prototype.charCodeAt to accept every character and String.prototype.toLowerCase to be case insensitive.

/**
 * @param {String} name you want to convert into a number.
 * @param {Array} [range] defaults to `[0, 9]`.
 * @returns {Number} num.
 */

function numerology (name, range) {
  if (arguments.length === 1) range = [0, 9]

  const inf = range[0]
  const sup = range[1]

  var num = name.split('')
                .map((x) => x.toLowerCase().charCodeAt())
                .reduce((a, b) => a + b)

  if (num < inf) num += inf
  if (num > sup) num = (num % sup) + inf

  return num
}

module.exports = numerology

License

MIT