app.js

// ==UserScript==
// @name         DLsite Master's Dream
// @description  DLsiteのプレミアムな購入履歴.jsonをお届けします
// @version      1.2
// @author       Marco
// @homepage     https://marco.plus
// @namespace    https://marco.plus
// @website      https://twitter.com/Marco_utau
// @match        https://www.dlsite.com/home/mypage/userbuy
// @match        https://www.dlsite.com/home/mypage/userbuy/*
// @icon         https://www.google.com/s2/favicons?sz=64&domain=dlsite.com
// @grant        none
// ==/UserScript==

(function() {
    'use strict';
    const landmarkElement = document.querySelector("#unpaid_list");
    const button = document.createElement("button");
    button.addEventListener("click", ()=>{
        const itemElements = document.querySelectorAll(".work_list_main tr:not(.item_name)");
        const items = Array.from(itemElements).map(element => {
            const date = element.querySelector(".buy_date").textContent.trim();
            const workNameElement = element.querySelector(".work_name");

            const title = workNameElement.textContent.trim();
            const anchorElement = workNameElement.querySelector("a");
            const artistName = element.querySelector(".maker_name").textContent.trim();
            const artistUrl = element.querySelector(".maker_name a").href;

            return {
                date,
                title,
                url: anchorElement ? anchorElement.href : undefined, // 特典などの商品ページがないケースがあるのでこんな感じにしている
                artistName,
                artistUrl
            }
        });

        const jsonText = JSON.stringify(items);
        const jsonBlob = new Blob([jsonText], {type: "application/json"});

        const linkElm = document.createElement("a");
        linkElm.href = URL.createObjectURL(jsonBlob);
        linkElm.target = "_self";

        const now = new Date();
        linkElm.download = `${now.getFullYear()}-${(now.getMonth() + 1).toString().padStart(2, "0")}-${now.getDate().toString().padStart(2, "0")
    }_${now.getHours().toString().padStart(2, "0")}-${now.getMinutes().toString().padStart(2, "0")}-${now.getSeconds().toString().padStart(2, "0")}`;
        linkElm.click();
    });

    button.textContent = "Save JSON";
    landmarkElement.insertAdjacentElement("beforebegin", button);
})();