function jsStartSearch() {
	if(document.getElementById('txtZoek').value.length < 3){
		alert('Voer minimaal 3 karakters in.');
		return false;
	} else {
		document.getElementById('modus').value = 'zoekresultaten';
		document.getElementById('frmZoek').submit();
	}
}

function keyDown(field, evt) {
	var keyCode = evt.which ? evt.which : evt.keyCode;
	if (keyCode == 13) {
		return jsStartSearch();
	}
}