const options = {
method: 'PUT',
headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
body: JSON.stringify({chapters: [{title: '<string>', start: 43200}]})
};
fetch('https://convertly.sh/api/video/streams/{id}/chapters', options)
.then(res => res.json())
.then(res => console.log(res))
.catch(err => console.error(err));