util-helpers

import { randomInt, toNumber } from 'ut2';
const letter = 'abcdefghijklmnopqrstuvwxyz';
const chars = {
    number: '0123456789',
    lower: letter,
    upper: letter.toUpperCase()
};
const allChars = chars.number + chars.lower + chars.upper;
/**
 * @private
 * @param {number} len 长度
 * @param {string} pool 字符池
 * @param {string} [prefix=''] 前缀部分，不计入长度
 * @returns {string}
 */
function internalRandomString(len, pool, prefix = '') {
    while (len-- > 0) {
        const r = pool[randomInt(0, pool.length - 1)];
        return internalRandomString(len, pool, prefix + r);
    }
    return prefix;
}
/**
 * 生成随机字符串
 *
 * @function
 * @alias module:Other.randomString
 * @since 4.8.0
 * @param {number} [len=0] 长度，默认`0`
 * @param {'number' | 'lower' | 'upper' | string | Array<'number' | 'lower' | 'upper'>} [pool='0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'] 字符池，默认为数字和大小写字母。支持设置类型`number` `lower` `upper` 或字符串，也支持数组组合。
 * @returns {string} 随机字符串
 * @example
 *
 * randomString(5); // slk23
 * randomString(8); // 71mHqo2A
 *
 * // 自定义允许的字符
 * randomString(5, 'abc'); // ccbcb
 * randomString(8, 'abcefg'); // bcgcfabg
 *
 * // 使用数组组合
 * randomString(5, ['number', 'lower']); // 1a2b3
 * randomString(8, ['upper', 'number']); // A1B2C3D4
 *
 */
const randomString = function (len = 0, pool) {
    let _pool;
    if (Array.isArray(pool)) {
        _pool = pool.map((p) => chars[p]).join('');
    }
    else if (typeof pool !== 'string') {
        _pool = allChars;
    }
    else if (chars[pool]) {
        _pool = chars[pool];
    }
    else {
        _pool = pool;
    }
    return internalRandomString(toNumber(len), _pool);
};
export default randomString;
randomString.js
