Amazon.co.jpのURLを短くするTampermonkey用UserScript

amazon-url-shortener.js

// ==UserScript==
// @name         Amazon URL Shortener JP (ISBN-10 first, else 13->10, else ASIN)
// @namespace    http://tampermonkey.net/
// @version      1.1
// @description  Shorten Amazon.co.jp URLs to /dp/ISBN-10 (books) or /dp/ASIN (others). If only ISBN-13 exists and starts with 978, convert to ISBN-10.
// @match        https://www.amazon.co.jp/*
// @grant        none
// ==/UserScript==
(() => {
  /** utils **/
  const onlyDigitsX = s => s.replace(/[^\dXx]/g, '');
  const isASIN   = s => /^[A-Z0-9]{10}$/.test(s);
  const isISBN10 = s => /^\d{9}[\dX]$/i.test(s);
  const isISBN13 = s => /^(97[89])\d{10}$/.test(s);

  // ISBN-13 (978xxxxxxxxxxx) -> ISBN-10（※979は変換不可）
  const isbn13to10 = (isbn13) => {
    const d = isbn13.replace(/\D/g, '');
    if (!/^978\d{10}$/.test(d)) return null; // 978以外は不可
    const core9 = d.slice(3, 12);            // 12桁中、出版社+書名の9桁
    // ISBN-10 チェックデジット計算
    let sum = 0;
    for (let i = 0; i < 9; i++) {
      sum += (10 - i) * parseInt(core9[i], 10);
    }
    const mod = sum % 11;
    const check = (11 - mod) % 11;
    const cd = (check === 10) ? 'X' : String(check);
    return core9 + cd;
  };

  // URL から ASIN を拾う
  const getASINFromUrl = (url) => (
    url.match(/\/dp\/([A-Z0-9]{10})(?:[/?#]|$)/)?.[1] ||
    url.match(/\/gp\/product\/([A-Z0-9]{10})(?:[/?#]|$)/)?.[1] ||
    url.match(/\/exec\/obidos\/ASIN\/([A-Z0-9]{10})(?:[/?#]|$)/)?.[1] ||
    url.match(/\/([A-Z0-9]{10})(?:[/?#]|$)/)?.[1] ||
    null
  );

  // DOM から ASIN（保険）
  const getASINFromDom = () => {
    const el = document.querySelector('[data-asin]');
    const v = el?.getAttribute('data-asin');
    return (v && isASIN(v)) ? v : null;
  };

  // 詳細欄テキスト収集
  const collectDetailText = () => {
    const selectors = [
      '#detailBullets_feature_div',
      '#detailBulletsWrapper_feature_div',
      '#detailBulletsWrapper',
      '#productDetails_detailBullets_sections1',
      '#productDetails_techSpec_section_1',
      '#productDetails_techSpec_section_2',
      '#prodDetails',
      '#detailBullets',
      '#detailBulletsReverse',
      '#productDetails_db_sections',
    ];
    let text = '';
    for (const sel of selectors) {
      const n = document.querySelector(sel);
      if (n) text += '\n' + n.innerText;
    }
    if (!text.trim()) text = document.body?.innerText || '';
    return text;
  };

  const getISBN10FromDom = () => {
    const txt = collectDetailText();
    // 明示の「ISBN-10:」優先（ハイフン/空白許容）
    const m = txt.match(/ISBN[\s\-]*10[^0-9X]*([0-9Xx\-\s]{10,15})/);
    if (m) {
      const cand = onlyDigitsX(m[1]).toUpperCase();
      if (isISBN10(cand)) return cand;
    }
    // 補助: 10桁候補の周辺に ISBN 文言がある場合のみ
    const generic = txt.match(/\b[0-9]{9}[0-9Xx]\b/g);
    if (generic) {
      for (const s of generic) {
        const idx = txt.indexOf(s);
        const around = txt.slice(Math.max(0, idx - 24), idx + s.length + 24);
        if (/ISBN/i.test(around)) {
          const cand = s.toUpperCase();
          if (isISBN10(cand)) return cand;
        }
      }
    }
    return null;
  };

  const getISBN13FromDom = () => {
    const txt = collectDetailText();
    // 「ISBN-13: 978-...」のような明示表記
    const m = txt.match(/ISBN[\s\-]*13[^0-9]*([0-9\-\s]{13,20})/i);
    if (m) {
      const cand = m[1].replace(/\D/g, '');
      if (isISBN13(cand)) return cand;
    }
    // 広めに 978/979 始まり13桁（ハイフン区切り対応）
    const all13 = txt.match(/(97[89][\s\-]*\d[\s\-]*\d[\s\-]*\d[\s\-]*\d[\s\-]*\d[\s\-]*\d[\s\-]*\d[\s\-]*\d[\s\-]*\d[\s\-]*\d[\s\-]*\d)/g);
    if (all13) {
      for (const raw of all13) {
        const cand = raw.replace(/\D/g, '');
        if (isISBN13(cand)) return cand;
      }
    }
    return null;
  };

  const toShortUrl = (code) => `https://www.amazon.co.jp/dp/${code}`;

  const run = () => {
    const url = location.href;

    // 優先: ISBN-10 -> (無ければ) ISBN-13→10 -> (無ければ) ASIN
    let code = null;

    const isbn10 = getISBN10FromDom();
    if (isbn10) {
      code = isbn10;
    } else {
      const isbn13 = getISBN13FromDom();
      const isbn10from13 = isbn13 ? isbn13to10(isbn13) : null;
      if (isbn10from13) {
        code = isbn10from13;
      } else {
        const asin = getASINFromUrl(url) || getASINFromDom();
        if (asin) code = asin;
      }
    }

    if (!code) {
      console.log('[Amazon Shortener] code not found');
      return;
    }

    const shortUrl = toShortUrl(code);
    if (url !== shortUrl) {
      history.replaceState(null, '', shortUrl);
      console.log('[Amazon Shortener] shortened ->', shortUrl);
    }
  };

  // 初回（SPA対策の遅延）
  const trigger = () => setTimeout(run, 800);
  trigger();

  // SPA/遅延ロード対応（デバウンス）
  let lastUrl = location.href;
  let timer = null;
  const onDomChange = () => {
    const changed = location.href !== lastUrl;
    if (changed) lastUrl = location.href;
    clearTimeout(timer);
    timer = setTimeout(run, changed ? 800 : 1200);
  };
  new MutationObserver(onDomChange).observe(document, { subtree: true, childList: true });
})();