qbittorrent-webui-cjratliff.com/private/views/cookies.html

<style>
    #manageCookiesContainer {
        margin: 10px;

        .buttonContainer {
            text-align: center;
            margin-top: 1em;
        }
    }

    #manageCookiesTable {
        tbody {
            td input {
                width: 140px;
            }

            td.expDate input {
                width: 190px;
            }
        }

        thead td {
            width: 150px;

            .expDate {
                width: 200px;
            }

            .actionColumn {
                width: 30px;
            }
        }

        .removeCookie,
        .addCookie {
            height: 16px;
            width: 16px;
            padding-left: 10px;
            vertical-align: middle;
            cursor: pointer;
        }
    }

</style>

<div id="manageCookiesContainer">
    <table id="manageCookiesTable">
        <thead>
            <tr>
                <td class="domain">Domain</td>
                <td class="path">Path</td>
                <td class="name">Name</td>
                <td class="value">Value</td>
                <td class="expDate">Expiration Date</td>
                <td class="actionColumn"></td>
            </tr>
        </thead>
        <tbody>
            <tr class="invisible newRow">
                <td class="domain"><input type="text" aria-label="Domain" autocomplete="off" autocorrect="off" autocapitalize="none"></td>
                <td class="path"><input type="text" aria-label="Path" autocomplete="off" autocorrect="off" autocapitalize="none"></td>
                <td class="name"><input type="text" aria-label="Name" autocomplete="off" autocorrect="off" autocapitalize="none"></td>
                <td class="value"><input type="text" aria-label="Value" autocomplete="off" autocorrect="off" autocapitalize="none"></td>
                <td class="expDate"><input type="datetime-local" aria-label="Expiration Date"></td>
                <td><img class="removeCookie" src="images/list-remove.svg" alt="Remove"></td>
            </tr>
        </tbody>
        <tfoot>
            <tr>
                <td></td>
                <td></td>
                <td></td>
                <td></td>
                <td></td>
                <td><img class="addCookie" src="images/list-add.svg" alt="Add Cookie"></td>
            </tr>
        </tfoot>
    </table>

    <div class="buttonContainer">
        <button type="button" id="saveButton">Save</button>
    </div>
</div>

<script>
    "use strict";

    window.qBittorrent ??= {};
    window.qBittorrent.ManageCookies ??= (() => {
        const exports = () => {
            return {
                setup: setup
            };
        };

        const addCookie = function() {
            const newRow = document.querySelector("#manageCookiesTable tr.newRow").cloneNode(true);
            newRow.querySelector(".removeCookie").addEventListener("click", (event) => {
                deleteCookie(event.target);
            });
            newRow.classList.remove("invisible");
            document.querySelector("#manageCookiesTable tbody").append(newRow);
            return newRow;
        };

        const deleteCookie = function(element) {
            element.closest("tr").destroy();
        };

        const save = function() {
            const rows = [...document.querySelectorAll("#manageCookiesTable tbody tr")].filter(e => !e.hasClass("invisible"));
            const cookies = rows.map(row => {
                const expDateValue = row.querySelector("td.expDate input").valueAsNumber;
                // remove ms from string
                const expDate = Number.isInteger(expDateValue) ? Number(String(expDateValue).slice(0, -3)) : 0;

                return {
                    domain: row.querySelector("td.domain input").value,
                    path: row.querySelector("td.path input").value,
                    name: row.querySelector("td.name input").value,
                    value: row.querySelector("td.value input").value,
                    expirationDate: expDate,
                };
            });

            new Request({
                url: "api/v2/app/setCookies",
                method: "post",
                noCache: true,
                data: {
                    cookies: JSON.stringify(cookies)
                },
                onFailure: (response) => {
                    let error = "Unable to save cookies";
                    if (response?.responseText)
                        error += `: ${response.responseText}`;
                    alert(error);
                },
                onSuccess: (response) => {
                    window.qBittorrent.Client.closeWindow("cookiesPage");
                }
            }).send();
        };

        const loadCookies = function() {
            new Request.JSON({
                url: "api/v2/app/cookies",
                method: "get",
                onFailure: (response) => {
                    let error = "Unable to load cookies";
                    if (response?.responseText)
                        error += `: ${response.responseText}`;
                    alert(error);
                },
                onSuccess: (response) => {
                    for (const cookie of response) {
                        const row = addCookie();
                        row.querySelector("td.domain input").value = cookie.domain;
                        row.querySelector("td.path input").value = cookie.path;
                        row.querySelector("td.name input").value = cookie.name;
                        row.querySelector("td.value input").value = cookie.value;
                        if (cookie.expirationDate > 0) {
                            // remove seconds + milliseconds, if any, to ensure seconds aren't displayed in input field
                            const date = new Date(cookie.expirationDate * 1000);
                            date.setSeconds(0);
                            date.setMilliseconds(0);
                            row.querySelector("td.expDate input").valueAsNumber = date.getTime();
                        }
                    }
                }
            }).send();
        };

        const setup = function() {
            loadCookies();

            document.querySelector(".addCookie").addEventListener("click", (event) => {
                addCookie();
            });

            document.querySelector("#saveButton").addEventListener("click", (event) => {
                save();
            });
        };

        return exports();
    })();
    Object.freeze(window.qBittorrent.ManageCookies);

    window.qBittorrent.ManageCookies.setup();
</script>