Simple fetch() sample

fetch.js

fetch(`/api/following/`, {
    method: "POST",
    headers:{
        'Content-Type': 'application/json'
    },
    body: JSON.stringify({
        followerUsername: loginName,
        followingUsername: nowname
    })
})
    .then(res => res.json().then(data => ({status: res.status, body: data})))
    .then(res => {
        if (res.status === 200 && res.body === true) {
            this.status = 'unfollow'
        }

    })