Getting a roblox remote function script return to behave exactly how you want is one of those "aha!" moments every developer hits when they move past basic building and into serious game logic. If you've spent any time at all in Studio, you probably already know about RemoteEvents—they're great for shouting a message across the server-client divide. But RemoteFunctions are the smarter, more talkative cousins. They don't just send a message; they wait for an answer, which is where that crucial "return" comes into play.
Think of a RemoteEvent like a walkie-talkie where you shout "The bridge is open!" and then turn the thing off. A RemoteFunction, however, is more like a phone call. You ask, "Hey, how much gold does this player have?" and you sit there, holding the phone to your ear, until the person on the other end gives you a number. If that number never comes back, you're just standing there forever. That's essentially what happens in your code when a return fails.
Why the Return Value Changes Everything
In the standard Roblox workflow, the server and the client live in two totally different worlds. The client (the player's computer) is untrustworthy and prone to lag. The server is the "source of truth." Most of the time, you want the client to ask the server for information.
When you use a roblox remote function script return, you're creating a bridge that allows data to flow back to the requester. Let's say you have a shop UI. The player clicks "Buy Sword." The client script shouldn't just assume the player has enough money. Instead, the client "invokes" a RemoteFunction on the server. The server checks the player's DataStore, realizes they're broke, and returns false. The client receives that false and displays a "You're too poor" message. Without the return, the client is just guessing.
Setting Up the Server-Side Logic
To get a return value, you have to set up what's called a "callback" on the server. This is basically telling the server, "Whenever someone calls this function, run this specific block of code and send back the result."
In your server script, you'd usually see something like remoteFunction.OnServerInvoke. This is where the magic happens. A common mistake I see beginners make is forgetting that the first argument passed to OnServerInvoke is always the player who called it. Even if you don't send any data from the client, the server still knows who's asking.
```lua -- Server Script local remoteFunction = game.ReplicatedStorage.CheckBalance
remoteFunction.OnServerInvoke = function(player) local balance = player.leaderstats.Gold.Value return balance -- This is the "return" we're talking about! end ```
On the client side, you'd call this using :InvokeServer(). The script will literally pause at that line until the server finishes its job and sends that balance back. It's clean, it's synchronous (mostly), and it makes your logic way easier to follow than trying to chain multiple RemoteEvents together.
The Danger of the "Infinite Yield"
Here is the catch—and it's a big one. Because RemoteFunctions wait for a response, they "yield" the script. This means your code stops dead in its tracks at the line where you invoked the function. If the server script runs into an error, hits an infinite loop, or just forgets to return something, your client script is going to hang indefinitely.
I've seen plenty of games where the UI just stops responding because a dev called a RemoteFunction that never returned. If the player clicks a "Join Match" button and that script yields forever, they can't click anything else, and it looks like the game crashed. To avoid this, you've got to make sure your server-side code is robust. Always ensure there's a return path, even if it's just returning nil or false to signify that something went wrong.
Security and the "Never Trust the Client" Rule
We have to talk about security because it's the biggest pitfall with a roblox remote function script return. Since the server is waiting for the client (or vice versa), there's an opening for exploiters.
A common (and dangerous) mistake is setting up an OnClientInvoke. This is when the server asks the client for information. Don't do this. Seriously, just don't. If the server invokes a function on a client and that player is using an exploit, they can simply choose never to return a value. Since the server is now yielding, waiting for that player's computer to answer, you've just let a random person on the internet freeze your entire server thread.
Instead, always try to keep the "invocation" starting from the client and ending at the server. Let the client ask the questions and the server provide the answers. The server should be the boss.
Practical Examples of Returns in Action
So, where do you actually use this? One of the best spots is for Action Validation. Imagine a crafting system. The player wants to craft a potion. They have the ingredients in their local inventory, but you need to make sure they actually have them on the server.
The client sends the request: "Hey, can I craft this?" The server looks at the inventory, deletes the herbs, adds the potion, and then returns true. The client receives true and plays a cool "Success!" sound effect and animation.
If the server returns false (maybe the player tried to cheat or had lag), the client can show a "Crafting Failed" popup. This two-way communication makes the game feel responsive and professional.
Another great use case is fetching data. If you're building a leaderboard or a custom profile page, you don't want to load every single piece of player data the moment someone joins. That would be a laggy mess. Instead, when a player opens the profile tab, the client invokes a RemoteFunction to get that specific player's stats. The server fetches only what's needed and returns a table of data.
Working with Tables and Multiple Values
One of the coolest things about the roblox remote function script return is that you aren't limited to returning just one thing. You can return strings, booleans, numbers, or even massive tables. You can even return multiple variables at once!
```lua -- Server remoteFunction.OnServerInvoke = function(player) return "Success", 100, {Item1 = "Sword", Item2 = "Shield"} end
-- Client local status, score, inventory = remoteFunction:InvokeServer() ```
This flexibility is what makes it so much more powerful than a RemoteEvent. You get a full package of information delivered right back to the script that asked for it. Just remember that whatever you send across that bridge has to be "serializable." You can't really send complex objects like nested functions or certain internal Roblox metadata, but for 99% of game dev needs, standard data types work perfectly.
Final Thoughts on Optimization
While it's tempting to use RemoteFunctions for everything, remember that they are slightly "heavier" than RemoteEvents because of that waiting period. If you don't actually need a value back, just use a RemoteEvent. It's faster and doesn't risk hanging your scripts.
But when you need that confirmation—when you need to know for a fact that the server did what it was supposed to do—the roblox remote function script return is your best friend. Just keep your server code clean, handle your errors, and never, ever let the server wait on a client for an answer. Do that, and your game's logic will be rock solid. Happy scripting!