Response.ok

The ok read-only property of the Response interface contains a Boolean stating whether the response was successful (status in the range 200-299) or not.

var myOK = response.ok;

A Boolean.

In our Fetch Response example (see Fetch Response live) we create a new Request object using the Request() constructor, passing it a JPG path. We then fetch this request using fetch(), extract a blob from the response using Body.blob, create an object URL out of it using URL.createObjectURL, and display this in an <img>.

var myImage = document.querySelector('img');

var myRequest = new Request('flowers.jpg');

fetch(myRequest).then(function(response) {
  console.log(response.ok); // returns true if the response returned successfully
  response.blob().then(function(myBlob) {
    var objectURL = URL.createObjectURL(myBlob);
    myImage.src = objectURL;
  });
});

• ServiceWorker API
• HTTP access control (CORS)
• HTTP