JavaScript Fetch API post data not added to the Request body issue fixed by setting headers using `new Headers()`

fetch_post_data_not_added.js

// https://github.com/matthew-andrews/isomorphic-fetch/issues/34
// This helped me to solve the issue.

const myHeaders = new Headers();

myHeaders.append('Content-Type', 'application/json');

fetch('/contact-form', {
    method: 'POST',
    headers: myHeader,
    body: JSON.stringify(fields)
}).then(() => {
    dispatch(contactFormSubmitSuccess());
});