Fetch APIs
(and XMLHttpRequest) follow the same-origin policy. The browsers restrict cross-origin HTTP requests from within
scripts. A cross-origin request occurs when request a resource from one domain
to other domain (from domain1.com to domain2.com).
As an Example,
//
From http://domain1.com/
fetch('http://domain1/data.json')
.then(function(response) {
// Do
something with response
});
The browser only returns the response
if the server returns an Access-Control-Allow-Origin header specifying that the
origin has permission to request the resource.
Cross-Origin Warning message: - Cross-Origin Request Blocked: The Same
Origin Policy disallows reading the remote resource at http://domain1/data.json
(Reason: CORS request did not succeed).
In the Fetch APIs, we can use no-cors
mode to request opaque resources. The
cors by default.
As an Example,
fetch(url,
{ method: 'HEAD', mode: 'no-cors' })
.then(res => {
console.log(res);
if (res.ok) {
console.log('URL is exists.');
}
else {
console.log('URL does not exist.');
}
})
.catch(err => console.log('Error:', err));
Make sure you are either
making the same-origin requests or CORS is enabled on the server.
What Is fetch?
The Fetch API is a simple
interface for fetching resources. Fetch makes it easier to make web requests
and handle responses than with the older XMLHttpRequest.
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Anil Singh is an author, tech blogger, and software programmer. Book writing, tech blogging is something do extra and Anil love doing it. For more detail, kindly refer to this link..
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