XPath Change Notifier

xpath_change_notifier.js

// ==UserScript==
// @name         XPath Change Notifier
// @namespace    http://tampermonkey.net/
// @version      1.4
// @description  每分钟检测指定 XPath 元素是否发生变化
// @author       Bluefissure
// @match        https://us-store.msi.com/*
// @match        https://www.bestbuy.com/site/*
// @grant        GM_notification
// @grant        GM_setValue
// @grant        GM_getValue
// @grant        GM_deleteValue
// @grant        GM_listValues
// @grant        GM_registerMenuCommand
// ==/UserScript==

(function() {
    'use strict';

    const XPATHS = {
        "us-store.msi.com": '//div[@class="row"]/div/button[contains(@class, "btn add-cart-button")]',
        "www.bestbuy.com": '//div[contains(@class, "row m")]//button[contains(@class, "add-to-cart-button")]'
    };

    let changeDetected = false;

    function getXPathElement(xpath) {
        let result = document.evaluate(xpath, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null);
        return result.singleNodeValue ? result.singleNodeValue.innerText.trim() : null;
    }

    function checkForChanges() {
        let host = window.location.hostname;
        let path = window.location.pathname;
        if (!XPATHS[host]) return;

        let pageKey = `lastValue_${host}_${path}`;
        let currentValue = getXPathElement(XPATHS[host]);
        let previousValue = GM_getValue(pageKey, "");
        console.log(`目标元素:${XPATHS[host]}`);
        console.log(`currentValue:${currentValue}`);
        console.log(`previousValue:${previousValue}`);
        console.log(`changeDetected:${changeDetected}`);

        if (currentValue === null) {
            notifyChange("目标元素未找到", host);
            return;
        }

        if (currentValue !== previousValue) {
            if (previousValue.trim() === '') {
                location.reload();
            }
            GM_setValue(pageKey, currentValue);
            notifyChange(currentValue, host);
            changeDetected = true;
        } else {
            console.log("Sleeping 60 seconds...");
        }
    }

    function notifyChange(newValue, host) {
        GM_notification({
            title: `页面更新通知 (${host})`,
            text: `检测到目标元素变化: ${newValue}`,
            timeout: 5000,
            onclick: function() { window.focus(); }
        });
    }

    function waitForPageLoad(callback) {
        if (document.readyState === "complete") {
            callback();
        } else {
            window.addEventListener("load", callback);
        }
    }

    function clearStoredValues() {
        let keys = GM_listValues();
        keys.forEach(key => GM_deleteValue(key));
        alert("所有存储的数据已清除！");
    }

    GM_registerMenuCommand("清除存储数据", clearStoredValues);

    waitForPageLoad(() => {
        setInterval(() => {
            if (!changeDetected) {
                location.reload();
            }
        }, 60 * 1000);
        checkForChanges();
    });
})();