how to send JSON with fetch code example

Example 1: how to post data using fethch

fetch('url here', {
    method: 'POST',
    headers: {'Content-Type':'application/x-www-form-urlencoded'}, // this line is important, if this content-type is not set it wont work
    body: 'foo=bar&blah=1'
});

Example 2: .fetch method

fetch('http://example.com/data.json')
  .then(data => data);
  .catch(err => console.log(err));