GoogleSearchHelper.js

// ==UserScript==
// @name         Google Search Helper
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  My helper script for Google search
// @author       Yumenosuke Koukata
// @require      https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js
// @match        *://www.google.com/*
// @match        *://www.google.co.jp/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    // remove 'translate this page' link
    // note: If you use tab key to select link, these get in the way.
    $('.action-menu.ab_ctl').remove();
    $('.fl').remove();

    var selectedResultId = 0;
    var $pointer = null;

    const selectResult = function (newId) {
        var $els = $('h3.LC20lb');
        if(newId < 0 || newId >= $els.length) return; //Could modify for page nav...?
        $pointer = $('#result-pointer');
        if($pointer) $pointer.remove();
        selectedResultId = newId;
        var el = $els[newId];
        var $el = $(el);
        $el.html('<div id="result-pointer" style="position:absolute;left:-15px;">&gt;</div>' + $el.html());
        var rect = el.getBoundingClientRect();
        if (rect.top < 0 || rect.bottom > window.innerHeight) window.scrollTo(0, rect.top + window.pageYOffset - window.innerHeight / 2);
        var $lnk = $el.find('a');
        $lnk.focus();
    }

    const setCaretAtEnd = function (elem) {
        var elemLen = elem.value.length;
        elem.selectionStart = elemLen;
        elem.selectionEnd = elemLen;
        elem.focus();
        $pointer = null;
    }

    $(window).keydown(function(event) {
        var ret = true;
        switch(event.keyCode) {
            case 9: // tab
            case 192: // backquote
                {
                    $('#lst-ib').focus(function(event){
                        $pointer = $('#result-pointer');
                        if($pointer) pointer.remove();
                    });

                    selectResult(0);
                    break;
                }
            case 38: // down-arrow
            case 80: // p
                {
                    if($pointer!=null) {
                        selectResult(selectedResultId-1);
                        ret = false;
                    }
                    break;
                }
            case 40: // up-arrow
            case 78: // n
                {
                    if($pointer!=null) {
                        selectResult(selectedResultId+1);
                        ret = false;
                    }
                    break;
                }
            case 191: // slash
                {
                    var $searchField = $('#lst-ib');
                    if($searchField != null && !$searchField.is(":focus")) {
                        setCaretAtEnd($searchField[0]);
                        ret = false;
                    }
                    break;
                }
        }
        return ret;
    });
})();