JavaScript - Coger valor "fecha" de un formulario, dentro de la misma pagina

<form action="javascript:taulaVentesDia()" >

    <input type="date" name="dia">

    <input type="submit" value="Consultar">

</form>

<script language="Javascript">

	function taulaVentesDia(){

		$('taulaVentesDia').load("contingut/calendariVentesDia.php?dia=" + $("#dia").val());

	}

</script>

$diaSencer = $_GET['dia'];

<form onsubmit="return taulaVentesDia()" >

    <input type="date" name="dia">

    <input type="submit" value="Consultar">

</form>

<div id="miDiv"></div>

<script>

    function taulaVentesDia(){

        alert("K");

        $('#miDiv').load("contingut/calendariVentesDia.php?dia=" + $("#dia").val());

        return false;

    }

</script>

<form action="javascript:taulaVentesDia()" >

        	<input type="date" name="dia" id="dia">

            <input type="submit" value="Consultar">

        </form>