Query strings should be modeled as a multimap

As indicated by the Wikipedia page Query string:

While there is no definitive standard, most web frameworks allow multiple values to be associated with a single field (e.g. field1=value1&field1=value2&field2=value3).

And indeed, many web frameworks I have used adopt this approach:

• Django: https://docs.djangoproject.com/en/3.2/ref/request-response/#django.http.QueryDict.getlist
• Starlette: https://www.starlette.io/requests/#query-parameters
• nodejs/querystring: https://nodejs.org/api/querystring.html#querystringparsestr-sep-eq-options

Therefore, I suggest itty-router follow the same convention.

Currently, itty-router models query strings as a Obj:

https://github.com/kwhitley/itty-router/blob/e8e76c9be5496ce2494743fb20dff802c41eb176/src/itty-router.d.ts#L22

where Obj is actually a map from some string to some string:

https://github.com/kwhitley/itty-router/blob/e8e76c9be5496ce2494743fb20dff802c41eb176/src/itty-router.d.ts#L1-L3

I suggest introducing MultiObj as the data model of query strings:

export type MultiObj = {
    [propName: string]: string | Array<string>
}

I’d like to help if you @kwhitley are interested in this 😃

[oliverjam]

Would it not be better to stick to web standard APIs, since CF Workers/itty already rely on Request, Response etc? The URLSearchParams interface is specifically designed for this:

let query = new URLSearchParams("field1=value1&field1=value2&field2=value3");

query.get("field2"); // "value3"
query.get("field1") // "value1" (picks the first)
query.getAll("field1"); // ["value1", "value2"] (array of all matches)
query.getAll("field2"); // ["value3"] (always an array for type consistency)

for (let [name, value] of query) {
  console.log(name, value);
}
// field1 value1
// field1 value2
// field2 value3

[kwhitley]

This will be included in the next major release 😃