I’m writing a Discord bot running on NodeJS, although this question applies to numerous scenarios having nothing to do with Discord. I need to make a synchronous method (which must remain synchronous), which returns a Promise, block until the Promise is resolved. This must be accomplished in 100% pure Javascript (no JQuery, etc.)

Example…

function getServerUsers() {
    //This method must be synchronous so that it can be called from numerous other synchronous methods without having to make the latters synchronous.

    //The goal is to make this synchronous method block until the inner Promise is resolved (or otherwise finalized), so that its data can be synchronously returned.

    //I've tried multiple strategies for this method, including inner anonymous functions, assigning the value of 'res' inside the 'then', etc.

    try {
        const guild = client.guilds.cache.get(CONFIG.GUILD_ID);
        console.log("getServerUsers -> fetching users...");
        var res;

        guild.members.fetch()   //fetch returns Promise<Collection<string, GuildMember>>.  'await' cannot be used here without making getServerUsers asynchronous
            .then(  //'then' appears to not be waiting properly
                result => {
                    res = result;
                    console.log("getServerUsers -> returning: " + JSON.stringify(res));
                    return res;
                }
            )
            .catch(
                err => {
                    console.error("getServerUsers -> guild.members.fetch(): " + err);
                    return null;
                }
            );
    }
    catch (e) {
        console.error("getServerUsers: " + e);
        return null;
    }
}


function exampleMethod() {
    //This method must also remain synchronous, which prevents the inner use of 'await'.

    try {
        var users = getServerUsers();
        console.log("exampleMethod -> serverUsers: " + JSON.stringify(users));  //users has not been set at this point in execution
    }
    catch(e) {
        console.error("exampleMethod: " + e);
    }
}

exampleMethod();

Expected/desired output of executing exampleMethod(sensitive data has been replaced with X’s):

getServerUsers -> fetching users...

getServerUsers -> returning: [{"guildId":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","joinedTimestamp":1714947621595,"premiumSinceTimestamp":null,"nickname":null,"pending":false,"communicationDisabledUntilTimestamp":null,"userId":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","avatar":null,"flags":0,"displayName":"XXXXXX","roles":["XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"],"avatarURL":null,"displayAvatarURL":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"},{"guildId":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","joinedTimestamp":1714982725184,"premiumSinceTimestamp":null,"nickname":null,"pending":false,"communicationDisabledUntilTimestamp":null,"userId":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","avatar":null,"flags":0,"displayName":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","roles":["XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"],"avatarURL":null,"displayAvatarURL":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"}]

exampleMethod -> serverUsers: [{"guildId":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","joinedTimestamp":1714947621595,"premiumSinceTimestamp":null,"nickname":null,"pending":false,"communicationDisabledUntilTimestamp":null,"userId":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","avatar":null,"flags":0,"displayName":"XXXXXX","roles":["XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"],"avatarURL":null,"displayAvatarURL":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"},{"guildId":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","joinedTimestamp":1714982725184,"premiumSinceTimestamp":null,"nickname":null,"pending":false,"communicationDisabledUntilTimestamp":null,"userId":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","avatar":null,"flags":0,"displayName":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","roles":["XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"],"avatarURL":null,"displayAvatarURL":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"}]

Actual/undesired output of executing exampleMethod (sensitive data has been replaced with X’s):

getServerUsers -> fetching users...

exampleMethod -> serverUsers: undefined

getServerUsers -> returning: [{"guildId":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","joinedTimestamp":1714947621595,"premiumSinceTimestamp":null,"nickname":null,"pending":false,"communicationDisabledUntilTimestamp":null,"userId":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","avatar":null,"flags":0,"displayName":"XXXXXX","roles":["XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"],"avatarURL":null,"displayAvatarURL":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"},{"guildId":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","joinedTimestamp":1714982725184,"premiumSinceTimestamp":null,"nickname":null,"pending":false,"communicationDisabledUntilTimestamp":null,"userId":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","avatar":null,"flags":0,"displayName":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","roles":["XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX","XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"],"avatarURL":null,"displayAvatarURL":"XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"}]

I’ve tried multiple strategies for this method, including inner anonymous functions, assigning the value of ‘res’ inside the ‘then’, etc.