HTML - Necesito obtener una URL con la id de mis TABS

<script>

function openCity(evt, cityName) {

    var i, tabcontent, tablinks;

    tabcontent = document.getElementsByClassName("tabcontent");

    for (i = 0; i < tabcontent.length; i++) {

        tabcontent[i].style.display = "none";

    }

    tablinks = document.getElementsByClassName("tablinks");

    for (i = 0; i < tablinks.length; i++) {

        tablinks[i].className = tablinks[i].className.replace(" active", "");

    }

    document.getElementById(cityName).style.display = "block";

    evt.currentTarget.className += " active";

}

// Get the element with id="defaultOpen" and click on it

document.getElementById("defaultOpen").click();

</script>

<div class="tab">

  <button class="tablinks" onclick="openCity(event, 'London')">London</button>

  <button class="tablinks" onclick="openCity(event, 'Paris')">Paris</button>

  <button class="tablinks" onclick="openCity(event, 'Tokyo')">Tokyo</button>

</div>

<div id="London" class="tabcontent">

  <h3>London</h3>

  <p>London is the capital city of England.</p>

</div>

<div id="Paris" class="tabcontent">

  <h3>Paris</h3>

  <p>Paris is the capital of France.</p>

</div>

<div id="Tokyo" class="tabcontent">

  <h3>Tokyo</h3>

  <p>Tokyo is the capital of Japan.</p>

</div>

confirm(document.location + "#" + cityName);