@bugsnag/cuid/dist/lib/cuid.js

Collision-resistant ids optimized for horizontal scaling and performance. For node and browsers.

'use strict';

const isCuid = require('./is-cuid.js');
const pad = require('./pad.js');

/**
 * cuid.js
 * Collision-resistant UID generator for browsers and node.
 * Sequential for fast db lookups and recency sorting.
 * Safe for element IDs and server-side lookups.
 *
 * Extracted from CLCTR
 *
 * Copyright (c) Eric Elliott 2012
 * MIT License
 */

function createCuid (fingerprint) {
    const blockSize = 4,
    base = 36,
    discreteValues = Math.pow(base, blockSize);

    let c = 0;

    function randomBlock () {
        return pad((Math.random() *
        discreteValues << 0)
        .toString(base), blockSize);
    }

    function safeCounter () {
        c = c < discreteValues ? c : 0;
        c++; // this is not subliminal
        return c - 1;
    }

    function cuid () {
        // Starting with a lowercase letter makes
        // it HTML element ID friendly.
        var letter = 'c', // hard-coded allows for sequential access

        // timestamp
        // warning: this exposes the exact date and time
        // that the uid was created.
        timestamp = new Date().getTime().toString(base),

        // Prevent same-machine collisions.
        counter = pad(safeCounter().toString(base), blockSize),

        // A few chars to generate distinct ids for different
        // clients (so different computers are far less
        // likely to generate the same id)
        print = fingerprint(),

        // Grab some more chars from Math.random()
        random = randomBlock() + randomBlock();

        return letter + timestamp + counter + print + random;
    }

    cuid.fingerprint = fingerprint;
    cuid.isCuid = isCuid;

    return cuid;
}

module.exports = createCuid;