required field velidator in javascript

<script type="text/javascript">

function ValideInput() {
    if(document.getElementById('name').value == '') {
        alert('Please enter a username!');
        return false;
    }else{
        return true;
    }
}

<form action="randompage" onsubmit="return ValideInput();">
    <input id="name" type="text"><input type="submit" value="go">
</form>