rword/dist/Random.js

A cryptographically secure random generator for real English words. Contains 370,000 words.

import crypto from 'crypto';
export class Random {
    /**
     * Transform an integer to a floating point number.
     */
    static intToFloat(integer) {
        return integer / Math.pow(2, 64);
    }
    /**
     * Generate a random number between `0` (inclusive) and `1` (exclusive). A
     *  drop in replacement for `Math.random()`
     */
    static value() {
        return this.intToFloat(parseInt(crypto.randomBytes(8).toString('hex'), 16));
    }
    /**
     * Generate a random number between `min` (inclusive) and `max` (exclusive).
     */
    static range(min, max) {
        return Math.floor(this.value() * (max - min) + min);
    }
    /**
     * Generate a seeded random number between `0` (inclusive) and `1` (exclusive).
     */
    static seededValue(seedChars, counter) {
        const counterBuffer = Buffer.alloc(8);
        const seedBuffer = Buffer.from(seedChars);
        const hmac = crypto.createHmac('sha256', seedBuffer);
        counterBuffer.writeBigUInt64LE(BigInt(counter));
        hmac.update(counterBuffer);
        const hash = hmac.digest();
        const integer = hash.readBigUInt64LE(0);
        const value = Number(integer) / Math.pow(2, 64);
        return value;
    }
    /**
     * Shuffle the words in place.
     */
    static shuffle(words, seedChars) {
        let generations = 0;
        let temp = '';
        let i = 0;
        let j = 0;
        for (i = words.length - 1; i > 0; i -= 1) {
            if (seedChars) {
                j = Math.floor(this.seededValue(seedChars, generations++) * (i + 1));
            }
            else {
                j = Random.range(0, i + 1);
            }
            temp = words[i];
            words[i] = words[j];
            words[j] = temp;
        }
    }
    /**
     * Randomly generate numbers for indexes within the words array.
     *
     * @param length - The length of the words array.
     * @param count - How many indexes to generate.
     */
    static indexes(length, count) {
        const indexes = [];
        while (true) {
            const index = this.range(0, length);
            if (indexes.indexOf(index) == -1)
                indexes.push(index);
            if (indexes.length == count)
                break;
            else if (length < count && indexes.length == length)
                break;
        }
        return indexes;
    }
}
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