how to check if username already exists in database using javascript
<form onsubmit="return validacija()">
<table>
<tr>
<td>Username:</td>
<td><input type="text" id="user" name="user" list="list"></td>
<datalist id="list">
<option value="Tilen">
<option value="Marko">
<option value="Teja">
<option value="Tisa">
<option value="Rok">
<option value="Luka">
<option value="Mojca">
</datalist>
</tr>
</table>
</form>