如何在文本框文本更改时将下拉列表的选定索引设置为0？

Question

I am using a dropdown to populate a textbox. But if preferred value is not present in dropdown then user directaly enter value in that textbox.

If user selects value from dropdown first and then he don't want that value and he types another text in that textbox then at this time the dropdown should be set to index 0 as user is typing another value.

I used textchanged event of textbox but it is not working. Can anyone tell me how to write javascript for this? Thanks in advance.

Answer 1

This should work for you:

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');"/>