How would you model bitmask parameter using URL query string?

Question

I'm working on a web service that needs to accept categories and perform a search using those. Categories can be combined, hence bitmask comes to mind.

Example:

Spring = 1, Summer = 2, Autumn = 4, Winter = 8

Possible options:

1. ?categories=5 - not very user friendly/pretty
2. ?categories=1,4 - needs special parsing
3. ?categories=1&categories=4 - well supported but a bit verbose for a lot of categories
4. ?categories=Spring,Autumn - seems most user friendly

Is there any standard way or preferred way to model bitmask type data?

Answer 1

I'd suggest going for semantic clarity over compression, but leverage native functions like JSON.stringify() and JSON.parse() and model them as an array, e.g.

categories = ['spring', 'summer', 'winter']

This is like #4, but slightly different in that it's using JSON which you can generate and parse unambiguously.