Logical 'or' in Lua patterns?

Is it possible to achieve in Lua?

local noSlashEnding = string.gsub("slash\\ending\\string\\", "\\|/$", "")
-- noSlashEnding should contain "slash\\ending\\string"

local noSlashEnding2 = string.gsub("slash/ending/string/", "\\|/$", "")
-- noSlashEnding2 should contain "slash/ending/string"

The point here is the no acceptance of logical 'or' statements in Lua patterns.

EDIT: Just realized that is possible by doing this:

strng.gsub("slash\\ending\\string\\", "[\\/]$", "")

Although logical 'or' for patterns is still missing.