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

<style>
    #installSearchPluginContainer {
        margin: 10px;
    }

    #installSearchPluginContainer button {
        padding: 3px 20px;
    }

    #newPluginPath {
        width: 100%;
        line-height: 2em;
    }

</style>

<div id="installSearchPluginContainer">
    <h2>Plugin path:</h2>

    <div>
        <input type="text" id="newPluginPath" placeholder="URL or local directory" autocorrect="off" autocapitalize="none" />
        <div style="margin-top: 10px; text-align: center;">
            <button class="button" id="newPluginCancel" onclick="qBittorrent.SearchPlugins.closeSearchWindow('installSearchPlugin');">Cancel</button>
            <button class="button" id="newPluginOk" onclick="qBittorrent.InstallSearchPlugin.newPluginOk();">Ok</button>
        </div>
    </div>
</div>

<script>
    'use strict';

    if (window.qBittorrent === undefined) {
        window.qBittorrent = {};
    }

    window.qBittorrent.InstallSearchPlugin = (function() {
        const exports = function() {
            return {
                newPluginOk: newPluginOk
            };
        };

        const init = function() {
            new Keyboard({
                defaultEventType: 'keydown',
                events: {
                    'Enter': function(e) {
                        // accept enter key as a click
                        new Event(e).stop();

                        const elem = e.event.srcElement;
                        if ((elem.id === "newPluginPath") || (elem.id === "newPluginOk"))
                            newPluginOk();
                        else if (elem.id === "newPluginCancel")
                            window.qBittorrent.SearchPlugins.closeSearchWindow('installSearchPlugin');
                    }
                }
            }).activate();

            $('newPluginPath').select();
        };

        const newPluginOk = function() {
            const path = $("newPluginPath").get("value").trim();
            if (path)
                new Request({
                    url: 'api/v2/search/installPlugin',
                    noCache: true,
                    method: 'post',
                    data: {
                        sources: path,
                    },
                    onRequest: function() {
                        window.qBittorrent.SearchPlugins.closeSearchWindow('installSearchPlugin');
                    }
                }).send();
        };

        init();

        return exports();
    })();

    Object.freeze(window.qBittorrent.InstallSearchPlugin);
</script>