Fix the TypeScript types for .stringify() and .stringifyUrl() (#279)

Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>

index.d.ts

@@ -339,11 +339,18 @@ export interface StringifyOptions {
 	readonly skipEmptyString?: boolean;
 }
 
+export type Stringifiable = string | boolean | number;
+
+export type StringifiableRecord = Record<
+	string,
+	Stringifiable | Stringifiable[] | null | undefined
+>;
+
 /**
 Stringify an object into a query string and sort the keys.
 */
 export function stringify(
-	object: {[key: string]: any},
+	object: StringifiableRecord,
 	options?: StringifyOptions
 ): string;
 
@@ -358,9 +365,9 @@ export interface UrlObject {
 	readonly url: string;
 
 	/**
-	Qverrides queries in the `url` property.
+	Overrides queries in the `url` property.
 	*/
-	readonly query: Record<string, string | undefined | null>;
+	readonly query: StringifiableRecord;
 
 	/**
 	Overrides the fragment identifier in the `url` property.

index.test-d.ts

@@ -94,4 +94,19 @@ expectType<queryString.ParsedUrl>(
 // Extract
 expectType<string>(queryString.extract('http://foo.bar/?abc=def&hij=klm'));
 
-expectType<string>(queryString.stringifyUrl({url: 'https://sindresorhus.com', query: {foo: undefined}}));
+expectType<string>(
+	queryString.stringifyUrl({
+		url: 'https://sindresorhus.com',
+		query: {
+			fooArray: [
+				'a',
+				'b'
+			],
+			fooNumber: 1,
+			fooBoolean: true,
+			fooNull: null,
+			fooUndefined: undefined,
+			fooString: 'hi'
+		},
+	})
+);