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

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 💪

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.

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,
		},
	);
});

Yeah, that makes sense to me.

@sindresorhus I'll get this implemented 💪