Как по нажатой кнопке идентифицировать строку в таблице?

<table id="table_orders" border="green">
            <thread>
                <tr><th>Name</th><th>Value</th><th>Count</th><th><button class="add_order">add</button></th>
            </thread>
            <tr>
                <td>Coffee</td><td>100</td><td><input type="text" class="input_count" value="1"></td><td><button class="save_order" onclick="saveTR(this)">save</button></td>
            </tr>
            <tr>
                <td>Tea</td><td>200</td><td><input type="text" class="input_count" value="2"></td><td><button class="save_order" onclick="saveTR(this)">save</button></td>
            </tr>
        </table>

function saveTR(xThis){
                console.log(xThis)
}