add-all-following-to-list.js

// Please paste to browser console
(async () => {
    const listIdRe = /\/web\/timelines\/list\/([0-9]+)/g.exec(location.pathname)
    if (listIdRe == null) throw "Please open timeline of target list"
    const listId = listIdRe[1]

    const initialState = JSON.parse(document.getElementById("initial-state").innerText)
    const token = initialState.meta.access_token
    const myUserID = initialState.meta.me
    const headers = { Authorization: "Bearer " + token }
    var next = ""
    do {
        const res = await fetch("/api/v1/accounts/" + myUserID + "/following" + next, {
            headers,
        })
        if (res.status >= 400) throw await addRes.text()
        const accounts = await res.json()
        const addRes = await fetch("/api/v1/lists/" + listId + "/accounts", {
            method: "POST",
            body: JSON.stringify({
                account_ids: accounts.map(a => a.id),
            }),
            headers: {
                ...headers,
                "Content-Type": "application/json"
            },
        })
        if (addRes.status >= 400) throw await addRes.text()
        const next_ = /(\?max_id=.+?)>/.exec(res.headers.get("Link"))
        next = next_ == null ? "" : next_[1]
    } while(next !== "")
})()