const lkup = new LOOKUP;
const result = await lkup.deviceByName("M:OUTTMP");
In the snippet above const, new, await, and string should all be highlighted. Only the string and new are highlighted. It appears that Redmine has already fixed this in version 4 by using Rouge.
I tested this snippet on the Rouge site and it highlights correctly.
#19930 is related but in the context of bash.