The first part is answered in the FAQ as slain pointed out.
As for a workaround, you can wrap the body of the loop in a function and return early from that, e.g.
-- Print the odd numbers from 1 to 99
for a = 1, 99 do
(function()
if a % 2 == 0 then
return
end
print(a)
end)()
end
Or if you want both break and continue functionality, have the local function perform the test, e.g.
local a = 1
while (function()
if a > 99 then
return false; -- break
end
if a % 2 == 0 then
return true; -- continue
end
print(a)
return true; -- continue
end)() do
a = a + 1
end