<div class="dropdown">
    <button class="dropbtn">Phone</button>
    <div class="dropdown-content">
        <a href="Subpage.html#iphone" onclick="itemChoice('iphone')">iPhone </a>
        <a href="Subpage.html#Samsung" onclick="itemChoice('Samsung')">Samsung</a>
        <a href="Subpage.html#xiaomi" onclick="itemChoice('Xiaomi')">Xiaomi</a>
        <a href="Subpage.html#HTC" onclick="itemChoice('HTC')">HTC</a>
    </div>
</div>

var item;
function itemChoice(choice){
    item = choice;
}