Query.ts

export type Query = { [key: string]: Query } | Query[] | string
export namespace Query {
	export function parse(data: any | string): Query | undefined {
		return typeof data == "string"
			? data
					.split("&")
					.filter(p => !!p)
					.map<[string] | [string, string]>(p => p.split("=") as [string] | [string, string])
					.map<[string, string]>(p => [decode(p[0]), p[1] ? decode(p[1]) : ""])
					.map<[string[], string]>(p => [
						p[0].split("[").map(e => (e.endsWith("]") ? e.substr(0, e.length - 1) : e)),
						p[1],
					])
					.reduce<Query>((r: Query, p: [string[], string]) => reduce(r, p[0], p[1]) as Query, {})
			: undefined
	}
}
function decode(data: string): string {
	let result: string
	data = data.replace(/\+/g, " ")
	try {
		result = decodeURIComponent(data)
	} catch (error) {
		result = unescape(data)
	}
	return result
}
function reduce(previous: Query | undefined, property: string[], value: string): Query {
	const p = property.shift()
	let result: Query
	if (p == undefined)
		result = value
	else if (p == "") {
		result = Array.isArray(previous) ? [...previous] : previous ? [previous] : []
		result.push(reduce(undefined, property, value))
	} else {
		result = (typeof previous == "string" ? { _: previous } : previous ? { ...previous } : {}) as { [key: string]: Query }
		result[p] = reduce(result[p], property, value)
	}
	return result
}