I googled to find out. Link #2 was https://scratch.mit.edu/discuss/topic/331755/?page=1 but I didn't like how that answer had two variables. I found the output variable had a length that matched the counter variable. Which allows for removing the second variable.
I'm unable to add a post to that thread. So I'm making a new thread and hoping the next person googling it the best of luck.

define reverse(string)
set (my variable) to []
repeat until <(length of (my variable)) = (length of (string))>
set (my variable) to (join (letter ((length of (my variable)) + (1)) of (string)) (my variable))
end

This is really genius code

This screen shot is for anyone having problems or can't see it right

I mean, technically you shouldn't create guides like this. However, you can create a wiki article (under your wiki profile) if you have a wiki account.

Thanks @THEPiG22! My son got around to copying the code today and had trouble with the coloring. Likely the comment on the empty string helped him out as well. Your screenshot was perfect!

mmhmBeans wrote:

…you shouldn't create guides like this. … create a wiki article …

Thank you for the suggestion. I was trying to maintain whatever format led me to that initial answer to increase the chance the next person googling it could find it. I was annoyed I couldn't just add to that thread. Suppose it makes sense wiki's are a suggested alternative to necro.

I did some testing and it turns out that this is the fastest code:

define reverse text (str)
set [output v] to []
repeat (length of (str))
set [output v] to (join (letter ((length of (output)) + (1)) of (str)) (output))
end

I did 200,000 tests of strings from 20 to 72 characters long (example: .r'kR\fDBXqQ4uv9gL6ykqEy;24K6T;uzQSy,FL)

The first method did it in 13403 ms (13.403s)

define reverse text (your text)
set [count v] to [1]
set [text v] to []
repeat (length of (your text)) 
set [text v] to (join (letter (count) of (your text)) (text))
change [count v] by [1]
end

The second method did it in 14479 ms (14.479s)

define reverse(string)
set (my variable) to []
repeat until <(length of (my variable)) = (length of (string))>
set (my variable) to (join (letter ((length of (my variable)) + (1)) of (string)) (my variable))
end

The third method did it in 12263 ms (12.263s)

define reverse text (str)
set [output v] to []
repeat (length of (str))
set [output v] to (join (letter ((length of (output)) + (1)) of (str)) (output))
end

Spentinium wrote:

I did some testing and it turns out that this is the fastest code:

define reverse text (str)
set [output v] to []
repeat (length of (str))
set [output v] to (join (letter ((length of (output)) + (1)) of (str)) (output))
end

I did 200,000 tests of strings from 20 to 72 characters long (example: .r'kR\fDBXqQ4uv9gL6ykqEy;24K6T;uzQSy,FL)

The first method did it in 13403 ms (13.403s)

define reverse text (your text)
set [count v] to [1]
set [text v] to []
repeat (length of (your text)) 
set [text v] to (join (letter (count) of (your text)) (text))
change [count v] by [1]
end

The second method did it in 14479 ms (14.479s)

define reverse(string)
set (my variable) to []
repeat until <(length of (my variable)) = (length of (string))>
set (my variable) to (join (letter ((length of (my variable)) + (1)) of (string)) (my variable))
end

The third method did it in 12263 ms (12.263s)

define reverse text (str)
set [output v] to []
repeat (length of (str))
set [output v] to (join (letter ((length of (output)) + (1)) of (str)) (output))
end

Just use repeat with screen refresh and it will always be instant

THEPiG22 wrote:

Spentinium wrote:

I did some testing and it turns out that this is the fastest code:
-snip-

Just use repeat with screen refresh and it will always be instant

I don't think you understand what I'm doing. I'm comparing the speeds without screen refresh and with turbo mode. Computers aren't infinitely fast, after all.

Spentinium wrote:

I did some testing and it turns out that this is the fastest code:

define reverse text (str)
set [output v] to []
repeat (length of (str))
set [output v] to (join (letter ((length of (output)) + (1)) of (str)) (output))
end

… did it in 12263 ms (12.263s)

[]Tracking a count variable[] did it in 13403 ms (13.403s)
[]Ops method[] did it in 14479 ms (14.479s)

That's awesome. Thanks for coming up with the optimization and these tests!

The replacement on the loop makes sense;

(length of (string))

is faster than

<(length of (my variable)) = (length of (string))>

It is interesting tracking a second variable, count, slows it down less than running an extra “length of variable”.

ShawnFeatherly wrote:

It is interesting tracking a second variable, count, slows it down less than running an extra “length of variable”.

In Scratch, setting or changing a variable takes a lot of time compared to operations such as +, -, length of, etc.