custom headers are not added to Request object

Question

I\'m trying to use fetch api.

First i create a new Headers() object:

var oHeaders = new Headers({
    \'Accept\': \'applic         


        

Answer 1

When you set mode: 'no-cors'for a request, browsers won’t allow you to set any request headers other than CORS-safelisted request-headers. See the spec requirements:

To append a name/value (name/value) pair to a Headers object (headers), run these steps:

5. Otherwise, if guard is "request-no-cors" and name/value is not a CORS-safelisted request-header, return.

In that algorithm, return equates to “return without adding that header to the Headers object”.