Example of real-time search bar implementation in Phoenix LiveView and Tailwind. Working example on https://travelermap.net/parks/usa

1_searchbar_live.ex

defmodule TravelerWeb.SearchbarLive do
  use TravelerWeb, :live_view

  alias Phoenix.LiveView.JS
  alias Traveler.Places

  def mount(_params, _session, socket) do
    socket = assign(socket, places: [])
    {:ok, socket, layout: false}
  end

  def handle_event("change", %{"search" => %{"query" => ""}}, socket) do
    socket = assign(socket, :places, [])
    {:noreply, socket}
  end

  def handle_event("change", %{"search" => %{"query" => search_query}}, socket) do
    places = Places.search(search_query)
    socket = assign(socket, :places, places)

    {:noreply, socket}
  end

  def open_modal(js \\ %JS{}) do
    js
    |> JS.show(
      to: "#searchbox_container",
      transition:
        {"transition ease-out duration-200", "opacity-0 scale-95", "opacity-100 scale-100"}
    )
    |> JS.show(
      to: "#searchbar-dialog",
      transition: {"transition ease-in duration-100", "opacity-0", "opacity-100"}
    )
    |> JS.focus(to: "#search-input")
  end

  def hide_modal(js \\ %JS{}) do
    js
    |> JS.hide(
      to: "#searchbar-searchbox_container",
      transition:
        {"transition ease-in duration-100", "opacity-100 scale-100", "opacity-0 scale-95"}
    )
    |> JS.hide(
      to: "#searchbar-dialog",
      transition: {"transition ease-in duration-100", "opacity-100", "opacity-0"}
    )
  end
end

2_searchbar_live.html.heex

<div class="block max-w-xs flex-auto">
  <button
    type="button"
    class="hidden text-gray-500 bg-white hover:ring-gray-500 ring-gray-300 h-8 w-full items-center gap-2 rounded-md pl-2 pr-3 text-sm ring-1 transition lg:flex focus:[&:not(:focus-visible)]:outline-none"
    phx-click={open_modal()}
  >
    <svg viewBox="0 0 20 20" fill="none" aria-hidden="true" class="h-5 w-5 stroke-current">
      <path
        stroke-linecap="round"
        stroke-linejoin="round"
        d="M12.01 12a4.25 4.25 0 1 0-6.02-6 4.25 4.25 0 0 0 6.02 6Zm0 0 3.24 3.25"
      >
      </path>
    </svg>
    Find something...
  </button>
</div>

<div
  id="searchbar-dialog"
  class="hidden fixed inset-0 z-50"
  role="dialog"
  aria-modal="true"
  phx-window-keydown={hide_modal()}
  phx-key="escape"
>
  <div class="fixed inset-0 bg-zinc-400/25 backdrop-blur-sm opacity-100"></div>
  <div class="fixed inset-0 overflow-y-auto px-4 py-4 sm:py-20 sm:px-6 md:py-32 lg:px-8 lg:py-[15vh]">
    <div
      id="searchbox_container"
      class="mx-auto overflow-hidden rounded-lg bg-zinc-50 shadow-xl ring-zinc-900/7.5 sm:max-w-xl opacity-100 scale-100"
      phx-hook="SearchBar"
    >
      <div
        role="combobox"
        aria-haspopup="listbox"
        phx-click-away={hide_modal()}
        aria-expanded={@places != []}
      >
        <form action="" novalidate="" role="search" phx-change="change">
          <div class="group relative flex h-12">
            <svg
              viewBox="0 0 20 20"
              fill="none"
              aria-hidden="true"
              class="pointer-events-none absolute left-3 top-0 h-full w-5 stroke-zinc-500"
            >
              <path
                stroke-linecap="round"
                stroke-linejoin="round"
                d="M12.01 12a4.25 4.25 0 1 0-6.02-6 4.25 4.25 0 0 0 6.02 6Zm0 0 3.24 3.25"
              >
              </path>
            </svg>

            <input
              id="search-input"
              name="search[query]"
              class="flex-auto rounded-lg appearance-none bg-transparent pl-10 text-zinc-900 outline-none focus:outline-none border-slate-200 focus:border-slate-200 focus:ring-0 focus:shadow-none placeholder:text-zinc-500 focus:w-full focus:flex-none sm:text-sm [&::-webkit-search-cancel-button]:hidden [&::-webkit-search-decoration]:hidden [&::-webkit-search-results-button]:hidden [&::-webkit-search-results-decoration]:hidden pr-4"
              style={
                @places != [] &&
                  "border-bottom-left-radius: 0; border-bottom-right-radius: 0; border-bottom: none"
              }
              aria-autocomplete="both"
              aria-controls="searchbox__results_list"
              autocomplete="off"
              autocorrect="off"
              autocapitalize="off"
              enterkeyhint="search"
              spellcheck="false"
              placeholder="Find something..."
              type="search"
              value=""
              tabindex="0"
            />
          </div>

          <ul
            :if={@places != []}
            class="divide-y divide-slate-200 overflow-y-auto rounded-b-lg border-t border-slate-200 text-sm leading-6"
            id="searchbox__results_list"
            role="listbox"
          >
            <%= for place <- @places do %>
              <li id={"#{place.id}"}>
                <.link
                  navigate={~p"/places/#{place.slug}"}
                  class="block p-4 hover:bg-slate-100 focus:outline-none focus:bg-slate-100 focus:text-sky-800"
                >
                  <%= place.name %>
                </.link>
              </li>
            <% end %>
          </ul>
        </form>
      </div>
    </div>
  </div>
</div>

3_places.ex

defmodule Traveler.Places do
  import Ecto.Query, warn: false
  alias Traveler.Repo
  alias Traveler.Places.Place
  
  def search(search_query) do
    search_query = "%#{search_query}%"

    Place
    |> order_by(asc: :name)
    |> where([p], ilike(p.name, ^search_query))
    |> limit(5)
    |> Repo.all()
  end
end

4_SearchBar.ts

// This is optional phoenix client hook. It allows to use key down and up to select results.

export const SearchBar = {
  mounted() {
    const searchBarContainer = (this as any).el as HTMLDivElement
    document.addEventListener('keydown', (event) => {
      if (event.key !== 'ArrowUp' && event.key !== 'ArrowDown') {
        return
      }

      const focusElemnt = document.querySelector(':focus') as HTMLElement

      if (!focusElemnt) {
        return
      }

      if (!searchBarContainer.contains(focusElemnt)) {
        return
      }

      event.preventDefault()

      const tabElements = document.querySelectorAll(
        '#search-input, #searchbox__results_list a',
      ) as NodeListOf<HTMLElement>
      const focusIndex = Array.from(tabElements).indexOf(focusElemnt)
      const tabElementsCount = tabElements.length - 1

      if (event.key === 'ArrowUp') {
        tabElements[focusIndex > 0 ? focusIndex - 1 : tabElementsCount].focus()
      }

      if (event.key === 'ArrowDown') {
        tabElements[focusIndex < tabElementsCount ? focusIndex + 1 : 0].focus()
      }
    })
  },
}