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.

A boolean value.

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 Response.blob, create an object URL out of it using URL.createObjectURL(), and display this in an <img>.

const myImage = document.querySelector("img");

const myRequest = new Request("flowers.jpg");

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

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