How to set selected index of dropdown to 0 when text of textbox is changed?

function ResetDropDown(id) {
    document.getElementById(id).selectedIndex = 0;
}
function ResetTextBox(id) {
    document.getElementById(id).value = '';
}
<select id="MyDropDown" onchange="ResetTextBox('MyTextBox');">
    <option value="0">0</option>
    <option value="1">1</option>
    <option value="2">2</option>
</select>
<input id="MyTextBox" type="text" onkeypress="ResetDropDown('MyDropDown');"/>