I want to check if the user entered a date.
But I can't figure it out how to do it.

Here's some javascript code what i already got but doesn't work :

var valueDate = document.getElementById('Date').value;

if ( valueDate== null || valueDate== '')

{

    alert('Date is empty');

    return false;

}

And the HTML <input type=date name=Date id=Date/>
Thanks in advance!