A user script to make product images on BrickLink use a larger image file

BrickLinkHighResImages.js

// ==UserScript==
// @name         BrickLink high res images
// @version      0.1
// @description  Make product images on BrickLink use a larger image file
// @author       Tanner Bennett / @NSExceptional / u/ThePantsThief
// @match        https://bricklink.com/*
// @match        https://*.bricklink.com/*
// @match        https://store.bricklink.com/*
// @grant        none
// ==/UserScript==

function observe(selector, imgSelector) {
    // Call initially just to be safe;
    // The catalog for example loads instantly
    resizeProductRows(imgSelector);

    const observer = new MutationObserver(function(mutationsList, observer) {
        for(var mutation of mutationsList) {
            if (mutation.type == 'childList' && mutation.target.lastElementChild.className != 'blLILThumbImageOverlay') {
                resizeProductRows(imgSelector);
                break;
            }
        }
    });

    const element = $(selector).get(0);
    if (element) {
        observer.observe(element, {
            attributes: false, childList: true, subtree: true
        });
    }
}

function resizeProductRows(selector) {
    $(selector).each(function() {
        const $img = $(this);
        let orig = $img.attr('src');

        let newURL = orig
            .replace(/\/([A-Z])T\//, '/$1N/')
            .replace('/Thumb/', '/')
            .replace(/\.t\d\./, '.');
        $img.attr('src', newURL);
    });
}

$(document).ready(function() {
    observe('.store-content', '.item .image img');
    observe('#ItemEditForm table', '.blCatalogImagePopup img');
});