2019 Laravel Update, Never thought i will post this but for those developers like me using the browser fetch api on Laravel 5.8 and above. You have to pass your token via the headers parameter.
var _token = "{{ csrf_token }}";
fetch("{{url('add/new/comment')}}", {
method: 'POST',
headers: {
'X-CSRF-TOKEN': _token,
'Content-Type': 'application/json',
},
body: JSON.stringify(name, email, message, article_id)
}).then(r => {
return r.json();
}).then(results => {}).catch(err => console.log(err));