codenames/dist/core/codename.js

Converts numerical values into human-readable names following a specific theme (e.g., cities)

/* SPDX-FileCopyrightText: 2025-present Kriasoft */
/* SPDX-License-Identifier: MIT */
/**
 * Converts a number to a human-readable codename using the provided word list.
 * This function is used internally by themed word files.
 *
 * @param words - Array of words to use for codenames
 * @param input - The number to convert
 * @returns A string codename
 *
 * @example
 * ```typescript
 * const cities = ["paris", "london", "tokyo"];
 * codename(cities, 1234) // "london"
 * ```
 */
export function codename(words, input) {
    if (!Number.isFinite(input)) {
        throw new Error(`Invalid input: expected a finite number, got ${input}`);
    }
    if (words.length === 0) {
        throw new Error("Word list cannot be empty");
    }
    const hash = fnv1a(input);
    const index = Math.abs(hash) % words.length;
    return words[index];
}
/**
 * FNV-1a hash function for consistent deterministic output.
 *
 * @param input - Number to hash
 * @returns 32-bit hash value
 */
function fnv1a(input) {
    const FNV_PRIME = 0x01000193;
    const FNV_OFFSET_BASIS = 0x811c9dc5;
    let hash = FNV_OFFSET_BASIS;
    const bytes = numberToBytes(input);
    for (const byte of bytes) {
        hash ^= byte;
        hash = Math.imul(hash, FNV_PRIME);
    }
    return hash >>> 0;
}
/**
 * Convert number to byte array for hashing.
 *
 * @param num - Number to convert
 * @returns Array of bytes
 */
function numberToBytes(num) {
    const buffer = new ArrayBuffer(8);
    const view = new DataView(buffer);
    view.setFloat64(0, num, true);
    return Array.from(new Uint8Array(buffer));
}
export default codename;
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