If you want to send the JSON object to backend, you should convert the JSON to String format.
See below example,
const json_object = {name:'Nirmal', email: 'admin@owlcoders.com'};
Convert above object to string. Use this javascript function JSON.stringify()
to convert object to string
const stringed_json = JSON.stringify(json_object);
stringed_json
is now a string.
Now we can easily store this string to server