fetch("URL",{

        // method changes

        method: 'PUT',

        body: JSON.stringify({

            title: 'foo',

            body: 'bar',

            userId: 0

        }),

        headers: {

            "Content-type": "application/json; charset=UTF-8"

        }

    })

        // Transform the data into json

            .then((res) => res.json())

            .then((data) => {

                console.log(data);

            })

            .catch((error)=> {

                console.log(error);

            });