Keyboard Navigation for Google Search with j/k Keys

// ==UserScript==
// @name         Google Search Result Keyboard Focus Navigation
// @namespace    http://tampermonkey.net/
// @version      0.3
// @description  Move focus to links using the "j" and "k" keys
// @author
// @match        https://www.google.com/search?*
// @exclude
// @grant        none
// ==/UserScript==

;(function () {
  'use strict'

  // Add custom CSS to forcibly show the outline when focused
  const style = document.createElement('style')
  style.innerHTML = `
        /* Use !important to prevent being overridden by Google's custom styles */
        a:focus {
            outline: 1px dotted #212121 !important;
            outline: 5px auto -webkit-focus-ring-color !important;
        }
    `
  document.head.appendChild(style)

  let currentIndex = -1
  let resultLinks = []

  // Function to get search result links
  function refreshResults() {
    resultLinks = []
    const h3Elements = document.querySelectorAll('#search a h3')
    h3Elements.forEach(function (h3) {
      const a = h3.closest('a')
      if (a) {
        resultLinks.push(a)
      }
    })
  }

  // Get the initial set of search result links
  refreshResults()
  if (resultLinks.length > 0) {
    currentIndex = 0
    focusResult(currentIndex)
  }

  // Focus the currently selected link and scroll to it
  function focusResult(index) {
    if (resultLinks[index]) {
      resultLinks[index].focus()
      resultLinks[index].scrollIntoView({ behavior: 'smooth', block: 'center' })
    }
  }

  // Listen for key presses
  document.addEventListener('keydown', function (e) {
    // Ignore key presses inside input fields or textareas
    const tagName = e.target.tagName.toLowerCase()
    if (tagName === 'input' || tagName === 'textarea') return

    // Pressing "j" focuses the next link
    if (e.key === 'j' || e.key === 'J') {
      if (currentIndex < resultLinks.length - 1) {
        currentIndex++
        focusResult(currentIndex)
      }
    }
    // Pressing "k" focuses the previous link
    else if (e.key === 'k' || e.key === 'K') {
      if (currentIndex > 0) {
        currentIndex--
        focusResult(currentIndex)
      }
    }
  })
})()