fix: handle bom in text and json (#1482)

* fix: handle bom in text and json

* add test for text and arraybuffer as well

src/body.js

@@ -145,8 +145,8 @@ export default class Body {
 	 * @return  Promise
 	 */
 	async json() {
-		const buffer = await consumeBody(this);
-		return JSON.parse(buffer.toString());
+		const text = await this.text();
+		return JSON.parse(text);
 	}
 
 	/**
@@ -156,7 +156,7 @@ export default class Body {
 	 */
 	async text() {
 		const buffer = await consumeBody(this);
-		return buffer.toString();
+		return new TextDecoder().decode(buffer);
 	}
 
 	/**

test/response.js

@@ -77,6 +77,21 @@ describe('Response', () => {
 		expect(res.headers.get('a')).to.equal('1');
 	});
 
+	it('should decode responses containing BOM to json', async () => {
+		const json = await new Response('\uFEFF{"a":1}').json();
+		expect(json.a).to.equal(1);
+	});
+
+	it('should decode responses containing BOM to text', async () => {
+		const text = await new Response('\uFEFF{"a":1}').text();
+		expect(text).to.equal('{"a":1}');
+	});
+
+	it('should keep BOM when getting raw bytes', async () => {
+		const ab = await new Response('\uFEFF{"a":1}').arrayBuffer();
+		expect(ab.byteLength).to.equal(10);
+	});
+
 	it('should support text() method', () => {
 		const res = new Response('a=1');
 		return res.text().then(result => {