I am finishing up my game and before release, I want to optimize it as much as possible. While writing the code, I realized that I have overused the WaitForChild function, and I don’t think this is optimal. With this post, I wanted to ask if someone could explain to me once and for all and in detail when I should use WaitForChild and when I could safely avoid it. Specifically, I would like to know when I could avoid using it depending on the scenarios, such as Scripts, LocalScripts, ServerStorage, ReplicatedStorage, Workspace, etc.
Reading the documentation, it says “This function does not yield if a child with the given name exists when the call is made,” and this has confused me because I don’t understand if using it on already present instances can be slower or not.
Thanks in advance to anyone who can help me fully understand how to use WaitForChild.
Is the script server-sided ? → do not use :WaitForChild() (with exceptions)
Is the script client-sided ? → probably use :WaitForChild() (with exceptions)
Exceptions may vary;
is content-streaming enabled ?
does the instance get created/parented by a script?
Are you accessing a child of an instance? For example; a decal under a part will always be there even with content-streaming, so there is no reason to use :WaitForChild()
Using :WaitForChild() is probably slower as you do a method call which then does the same thing, but the performance can’t be that much worse
ok, so in a nutshell, :WaitForChild just stops the script and waits until it finds that certain child, you ONLY need to do this if it is required for the script, like when people are working with characters and they do :WaitForChild(“Humanoid”) it is because they are affecting the humanoid and want to make sure that no matter what, it is found so it can be changed, for most cases, you can use :FindFirstChild for things that load immediately into the game, like if you have a part inside of the workspace, you dont have to wait for the child, you can literally do .Part or :FindFirstChild(“Part”), i use FindFirstChild a lot because It works fine, and anyways unless things are constantly deloading and reloading like the players character, then you can just use FindFirstChild because it doesnt yield the script but it still tries to get the object
if it gives you an error that it cant find the instance using FindFirstChild then you should probably use WaitForChild then
oh yeah i forgot to mention the client and server side of them, as the guy said above, dont ever use it on the server side because everything on the server is loaded, only use for client side because thats where everything is loading/replicating from the server
Thank you for the answers! I have a question: if I am “selecting” an object from a server-side script, do I not need to use WaitForChild in any case if the object is in the Workspace, ServerStorage, or ReplicatedStorage? In other words, does the server have access at any time to any object that is not dynamically created by scripts during game execution?