Set all Amazon searches to Prime automatically

May 30, 2024 at 09:53

Updated: 20 Feb 2025.

This topic was previously covered in the Firefox Modifications post, but this solution is much more convenient. By appending “&rh=p_85%3A2470955011” to the Amazon search URL, you can ensure that your search results always display Prime-eligible items. The parameter p_85 stands for “Amazon Prime,” and 2470955011 is the Prime filter identifier.

Here is a Tampermonkey script that automates this process for you. When you search, the page will reload with the Prime filter applied. This will add a second or two to your search time, but it’s likely something you would manually do anyway.

always_prime_search.js

// ==UserScript==
// @name         Amazon Prime Search Modifier
// @namespace    http://tampermonkey.net/
// @version      1.4
// @description  Automatically add Prime filter to Amazon search URLs using URLSearchParams
// @author       Johnny Quest
// @match        https://www.amazon.com/s*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    const primeFilterParam = 'p_85:2470955011';

    function modifySearchURL() {
        const url = new URL(window.location.href);
        const params = new URLSearchParams(url.search);
        let rh = params.get('rh') || '';

        // Check if the prime filter is already present
        if (!rh.includes(primeFilterParam)) {
            // Append the prime filter; if there are other filters, separate them with a comma
            rh = rh ? `${rh},${primeFilterParam}` : primeFilterParam;
            params.set('rh', rh);
            url.search = params.toString();

            // Replace the URL with the new parameters
            window.location.replace(url.toString());
        }
    }

    // Run the function on load. Optionally, you can attach this to events if needed.
    modifySearchURL();
})();

01 March 2025
- Fixed a page loop on adding additional search filters
20 February 2025
- It works now. Swapped popstate for MutationObserver

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Set all Amazon searches to Prime automatically