fix: handle bom in text and json (#1739)

* fix: handle bom in text and json
* add unit tests

package.json

@@ -39,7 +39,7 @@
     "dependencies": {
         "whatwg-url": "^5.0.0"
     },
-    "peerDependencies": { 
+    "peerDependencies": {
         "encoding": "^0.1.0"
     },
     "peerDependenciesMeta": {

src/body.js

@@ -114,9 +114,9 @@ Body.prototype = {
 	 * @return  Promise
 	 */
 	json() {
-		return consumeBody.call(this).then((buffer) => {
-			try {
-				return JSON.parse(buffer.toString());
+		return this.text().then((text) => {
+			try{
+				return JSON.parse(text); 
 			} catch (err) {
 				return Body.Promise.reject(new FetchError(`invalid json response body at ${this.url} reason: ${err.message}`, 'invalid-json'));
 			}
@@ -129,7 +129,7 @@ Body.prototype = {
 	 * @return  Promise
 	 */
 	text() {
-		return consumeBody.call(this).then(buffer => buffer.toString());
+		return consumeBody.call(this).then(buffer => new TextDecoder().decode(buffer));
 	},
 
 	/**

test/test.js

@@ -2479,6 +2479,21 @@ describe('Response', function () {
 		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', function() {
 		const res = new Response('a=1');
 		return res.text().then(result => {