Adds a button to @yaqwsx JLC PCB Component Catalog to send the (filtered) resistors to a parallel-resistor-finder so you can find parallel resistor combinations based only on resistors JLC has available (especially useful for "Basic" ones).

resistor-paralleler-for-jlcpcb-assembly-parts.js

// ==UserScript==
// @name         Resistor Paralleler For JLC Parts
// @namespace    https://gist.github.com/sleemanj/b5e75f18d7292ab43e37b96e2a7ef905
// @downloadURL  https://gist.github.com/sleemanj/b5e75f18d7292ab43e37b96e2a7ef905/raw/resistor-paralleler-for-jlcpcb-assembly-parts.js
// @updateURL  https://gist.github.com/sleemanj/b5e75f18d7292ab43e37b96e2a7ef905/raw/resistor-paralleler-for-jlcpcb-assembly-parts.js
// @version      0.3
// @description  Send the resistors to the resistor paralleler.  You must add Resistance as the last column in the table.
// @author       James Sleeman
// @match        https://yaqwsx.github.io/jlcparts/
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    function goToParalleler()
    {
        if(!document.querySelector('.w-full thead tr th:last-child').innerHTML.match(/Resistance/))
        {
            alert("The last column in the table must be Resistance");
            return false;
        }

        var howManyRows = 0;
        function forceTheLazyLoaderFirst()
        {
            if(howManyRows != document.querySelectorAll('.w-full tbody tr').length)
            {
              howManyRows = document.querySelectorAll('.w-full tbody tr').length;
              window.scrollBy({ left:0, top:document.body.scrollHeight, behaviour:'smooth'});
              window.setTimeout(forceTheLazyLoaderFirst, 500);
              return;
            }

            var bumps = [ ];
            var x = document.querySelectorAll('.w-full tbody tr td:last-child');
            for(var y = 0; y < x.length; y++) { if(x.item(y).innerHTML) bumps.push(x.item(y).innerHTML.replace(/\s+/,'')); };

            window.open( 'https://sparks.gogo.co.nz/resistor_paralleler.html?Bases=&Bumps='+encodeURIComponent(bumps.join(',')) );
            return true;
        }
        forceTheLazyLoaderFirst();
    }

    function setup()
    {
        window.setTimeout(setup, 1000);
        if(document.querySelector('.ourbutton')) return;
        if(!document.querySelector(".pt-4 button")) return;

        var a = document.createElement('button');
        a.innerText = 'Open Resistor Paralleler With These Results';
        a.onclick   = function(){
            goToParalleler();
        };
        a.className = 'flex-none ml-auto block flex-none bg-blue-500 hover:bg-blue-700 text-black py-1 px-2 rounded ourbutton';
        document.querySelector(".pt-4 button").parentNode.insertBefore(a, document.querySelector(".pt-4 button"));
    }

    setup();
})();