I think if you’re using the browser fetchAPI you need to create the headers from the constructor, I use this:
export function requester({ method, url, data, accept, content_type }, token) {
let body = typeof data === "string" ? data : JSON.stringify(data);
token = token ? token : "";
content_type = content_type ? content_type : "application/json";
accept = accept ? accept : "application/json";
if (process && process.server) {
const fetch = require("node-fetch");
let headers = {
"Bearer": token,
"Content-Type": content_type,
"Accept": accept
};
let request = {
method: method,
headers: headers,
body: body,
mode: "cors"
};
return fetch(url, request)
.then(response => response.json())
.catch(error => { return {error: error.message} });
} else {
let headers = new Headers({
"Bearer": token,
"Content-Type": content_type,
"Accept": accept
});
let request = new Request(url, {
method: method,
headers: headers,
body: body,
mode: "cors"
});
return fetch(request)
.then(response => response.json())
.catch(error => { return {error: error.message} });
}
}


















