function switch_page(valeur)

{

if
(document.getElementById("theme_recherche").value== 0) {location = '';}

else if (document.getElementById("theme_recherche").value == 1) {alert('Option 1')}
else if (document.getElementById("theme_recherche").value== 2) {alert('Option 2')}
else if (document.getElementById("theme_recherche").value== 3) {location = 'index.php?id=173'}

}