README.md

HOW TO INSTALL

1. Tampermonkeyを入れる Chrome, Firefox, Microsoft Edge, Safari
2. これをクリック→https://gist.github.com/Petitsurume/f7256fb115177bee73bead14d6a46f70/raw/nicommentpost.user.js
3. https://friends.nico/nicomment を開く
4. やったぜ。

これはWTFPLです。

nicommentpost.user.js

// ==UserScript==
// @name         NicommentPost
// @namespace    https://surume.tk
// @version      0.1
// @description  Nicommentにコメント投稿欄の追加
// @author       You
// @match        https://friends.nico/nicomment
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    // Your code here...
    
    var nowPosting = false
    var nowAjax = true
    var accessToken = ""
    
    var css = document.createElement("style")
    css.innerText = ".app{height:calc(100% - 2em);}"
    document.body.appendChild(css)
    var comment_form = document.createElement("form")
    comment_form.style.position="fixed"
    comment_form.style.bottom="0"
    comment_form.style.left = "10vw"
    comment_form.style.right = "10vw"
    comment_form.style.height="2em"
    comment_form.style.display="flex"
    comment_form.action = "javascript://"
    var comment_input = document.createElement("input")
    comment_input.disabled = true
    comment_input.type="text"
    comment_input.style.flex="8"
    comment_input.placeholder="コメントを入力"
    comment_input.onsubmit = alert
    comment_form.appendChild(comment_input)
    var comment_post_button = document.createElement("button")
    comment_post_button.disabled = true
    comment_post_button.style.backgroundColor = "orange"
    comment_post_button.innerText = "コメント"
    comment_post_button.style.flex="2"
    comment_post_button.type="submit"
    comment_form.onsubmit = function(){
        if(nowPosting || nowAjax) return
        nowPosting = true
        comment_post_button.disabled = true
        comment_post_button.innerText = "コメント中..."
        comment_input.disabled = true
        fetch("/api/v1/statuses",{
            headers: {"Authorization": "bearer "+accessToken, "Content-Type": "application/json"},
            method: 'POST',
            body: JSON.stringify({"status":comment_input.value,"in_reply_to_id":null,"media_ids":[],"sensitive":false,"spoiler_text":"","visibility":"public"})
        }).then(res => {
            return res.json()
        }).then(json => {
            comment_input.value = ""
            comment_input.disabled = false
            comment_post_button.disabled = false
            nowPosting = false
            comment_post_button.innerText = "コメント"
        })
    }
    comment_form.appendChild(comment_post_button)
    document.body.appendChild(comment_form)
    fetch("/web/getting-started", {credentials: 'include'}).then(res => {
        return res.text()
    }).then(res => {
        var dom = (new DOMParser()).parseFromString(res, "text/html")
        if(dom.getElementsByTagName("parsererror").length) return // パースエラー
        var infoJSON = JSON.parse(dom.getElementById("initial-state").innerText)
        console.log(infoJSON)
        accessToken = infoJSON.meta.access_token
        comment_input.disabled = false
        comment_post_button.disabled = false
        nowAjax = false
        setTimeout(function(){comment_input.focus()},1)
    })
})();