Update fetch()

js-fetch.md

@@ -37,11 +37,34 @@ fetch('/data.json', {
 
   headers: {
     'Accept': 'application/json'
-  }
+  },
+
+  credentials: 'same-origin', // send cookies
+  credentials: 'include',     // send cookies, even in CORS
+
 })
 ```
 
-##
+### Catching errors
+
+Non-2xx responses are still successful requests. Use another function to turn them to errors.
+
+```js
+fetch('/data.json')
+  .then(checkStatus)
+```
+
+```js
+function checkStatus (res) {
+  if (res.status >= 200 && res.status < 300) {
+    return res
+  } else {
+    var err = new Error(response.statusText)
+    err.response = response
+    throw err
+  }
+}
+```
 
 ## Using with node.js