Greasmonkey script to hide items on Amazon Fresh category pages that are not on my list, so I can find the stuff I do want. Right click an item picture, then click Not on my list to hide the item. Demo: https://www.youtube.com/edit?video_id=mTDQGyF3Zvs

FreshThresh.js

// ==UserScript==
// @name        FreshThresh
// @namespace   github.com/kielni
// @description Hide items from Amazon Fresh via right click menu
// @include     https://fresh.amazon.com/*
// @version     1
// @grant       none
// ==/UserScript==

/*
    This script hides prducts not on my list from Amazon Fresh,
    so I can find the stuff I do want.  It saves the set of hidden
    items in local storage.
*/

// add right click menu
if (!("contextMenu" in document.documentElement &&
      "HTMLMenuItemElement" in window)) return;

var body = document.body;
body.addEventListener("contextmenu", initMenu, false);
var menu = body.appendChild(document.createElement("menu"));
menu.outerHTML = '<menu id="userscript-hide" type="context">'+
                 '    <menuitem label="Not on my list"></menuitem>'+
                 '</menu>';
document.querySelector("#userscript-hide menuitem")
    .addEventListener("click", hideItem, false);

// wait for products (.resultSet) to load
var observer = new window.MutationObserver(mutationHandler);
var observerConfig = {
    childList: true, attributes: false, subtree: true
};
observer.observe (document, observerConfig);

function mutationHandler (mutationRecords) {
    mutationRecords.forEach(function (mutation) {
        if (mutation.type == "childList" && mutation.addedNodes.length) {
            for (var i = 0; i < mutation.addedNodes.length; i++) {
                var node = mutation.addedNodes.item(i);
                if (node.nodeType === 1 && node.classList.contains("resultSet")) {
                    hideItems();
                }
             }
        }
    });
}

// hide item ids from list of keys in local storage
function hideItems() {
    var hidden = getHidden();
    Object.keys(hidden).forEach(function(itemId) {
        var $item = jQuery("#"+itemId);
        $item.closest(".smallProduct").hide();
        console.log("hiding "+itemId+"\t"+hidden[itemId]);
    });
}

// get hidden items from local storage
function getHidden() {
    var hidden = unsafeWindow.localStorage.getItem("FreshThresh");
    return hidden ? JSON.parse(hidden) : {};
}

// show right click menu on click of image, and save item id as attribute
function initMenu(ev) {
    if (ev.target.localName !== "img") {
        return;
      }
      body.setAttribute("contextmenu", "userscript-hide");
      var itemId = jQuery(ev.target).closest(".itemPicture").attr("id");
      var menuitem = document.querySelector("#userscript-hide menuitem");
      menuitem.setAttribute("itemId", itemId);
}

// hide an item when it's clicked, and save to local storage for future pageloads
function hideItem(ev) {
    var menuitem = document.querySelector("#userscript-hide menuitem");
    var itemId = menuitem.getAttribute("itemId");
    var $item = jQuery("#"+itemId);
    $item.closest(".smallProduct").fadeOut();
    var title = $item.closest(".item").find(".title").text();
    var hidden = getHidden();
    if (!hidden[itemId]) {
        hidden[itemId] = title;
        unsafeWindow.localStorage.setItem("FreshThresh", JSON.stringify(hidden));
    }
}