Stupid is a number format used in socket.io. It is used in both sending and receiving messages, where it is used as the format of the message length.
Formally, the Stupid representation of a number is a string containing one byte between 0 and 9 corresponding to each digit in the decimal representation of that number. For example, the number 45 in stupid format would be
'\x04\x05' - that is, the byte value 4 and the byte value 5. "Conveniently", this is equivalent to the string representation of a number (eg.
'45'), if you subtract the ASCII value for the character
'0' from each character.