RocketChat/Rocket.Chat

import { settings } from '../../../settings/server';

export const validateUsername = (username: string): boolean => {
    const settingsRegExp = settings.get('UTF8_User_Names_Validation');
    const defaultPattern = /^[0-9a-zA-Z-_.]+$/;

    let usernameRegExp: RegExp;
    try {
        usernameRegExp = settingsRegExp ? new RegExp(`^${settingsRegExp}$`) : defaultPattern;
    } catch (e) {
        usernameRegExp = defaultPattern;
    }

    return usernameRegExp.test(username);
};