FEAT: implement support for boolean type

[scottenock]

Hey @sindresorhus , when implementing the parsing fix for PR #406 I noticed it would be pretty quick to add support for a boolean type. This allows the user to override the behaviour of parseBoolean.

I've updated the README and type definitions to include the new boolean type.

I've also updated the description of the types feature to be clearer. Let me know your thoughts!

[sindresorhus]

Thanks for implementing this. I think it should also accept 0 and 1 as those are commonly used as booleans.

[scottenock]

Good shout! I've added support for 0 and 1 when the boolean type is used.

I haven’t extended this to the parseBoolean option yet—wanted to check with you first @sindresorhus . If you think it makes sense, I’ll get it added. Otherwise, I believe the PR is good to go 💪

[sindresorhus]

I haven’t extended this to the parseBoolean option yet—wanted to check with you first @sindresorhus . If you think it makes sense, I’ll get it added. Otherwise, I believe the PR is good to go 💪

No, it should not. parseBooleans means that it would parse numbers as booleans, even if it's meant to be a number. For example, a query parameter that could be 0, 1, 2, 3, etc.

[julienw]

Hey folks,
question: what about ?booleanParam without a value? I feel like it should be true. But it's now parsed as "null".

Here is the added test:

test("types option: boolean type accepts an empty string as true", (t) => {
	t.deepEqual(
		queryString.parse("a&b", {
			parsebooleans: false,
			types: {
				a: "boolean",
				b: "boolean",
			},
		}),
		{
			a: true,
			b: true,
		},
	);
});

[sindresorhus]

Yeah, that makes sense to me.

[scottenock]

@sindresorhus I'll get this implemented 💪