feat(parseHeaders): make it case-insensitive

Author: coderbyheart

src/parseHeaders.spec.ts

@@ -13,7 +13,7 @@ void describe('parseHeaders()', () => {
 		const parsedHeaders = parseHeaders(headers)
 
 		assert.deepEqual(
-			parsedHeaders,
+			new Map(parsedHeaders.entries()),
 			new Map([
 				['content-type', 'application/json'],
 				['content-length', '1234'],
@@ -24,4 +24,12 @@ void describe('parseHeaders()', () => {
 
 	void it('should handle null values in headers', () =>
 		assert.deepEqual(parseHeaders(null), new Map()))
+
+	void it('should make header keys case-insensitive', () => {
+		const headers = {
+			'x-custom-header': 'value',
+		}
+		const parsedHeaders = parseHeaders(headers)
+		assert.equal(parsedHeaders.get('X-Custom-HEADER'), 'value')
+	})
 })

src/parseHeaders.ts

@@ -5,10 +5,29 @@
  */
 export const parseHeaders = (
 	headers: Record<string, string | undefined> | null,
-): Map<string, string | null> => {
+): ParsedHeaders => {
 	if (headers === null) return new Map()
-	return Object.entries(headers).reduce((h, [key, value]) => {
-		h.set(key.toLowerCase(), value ?? null)
-		return h
-	}, new Map())
+	return CaseInsensitiveMap(
+		Object.entries(headers).reduce((h, [key, value]) => {
+			h.set(key.toLowerCase(), value ?? null)
+			return h
+		}, new Map()),
+	)
 }
+
+export type ParsedHeaders = Pick<
+	Map<string, string | null>,
+	'get' | 'has' | 'size' | 'keys' | 'values' | 'entries' | 'forEach'
+>
+
+export const CaseInsensitiveMap = (
+	map: Map<string, string | null>,
+): ParsedHeaders => ({
+	get: (key) => map.get(key.toLowerCase()),
+	has: (key) => map.has(key.toLowerCase()),
+	size: map.size,
+	keys: () => map.keys(),
+	values: () => map.values(),
+	entries: () => map.entries(),
+	forEach: (callback, thisArg) => map.forEach(callback, thisArg),
+})