<script type="text/javascript">jQuery(function($){
    var isPlaceholderSupported = function () { 
        var o = document.createElement('input'); 
        return "placeholder" in o; 
    };
    if (!isPlaceholderSupported()) {
        var togglePlaceholderText = function (el) {    
            var color = '#999';
            var v = $.trim(el.val());
            var p = el.attr('placeholder'); 
            if (v == '') { 
                el.val(p); 
                el.css({'color':color}); 
            } else if (v == p) {
                el.val(''); 
                el.css({'color':''});
            } 
        };
        $('input[placeholder]')
            .each(function(){togglePlaceholderText($(this));})
            .click(function(){togglePlaceholderText($(this));})
            .blur(function(){togglePlaceholderText($(this));})
            .closest('form').submit(function(){$(this).find('input[placeholder]').each(function(){togglePlaceholderText($(this));})});
    }

    //alert pour montrer que cela fonctionne
    $('form').submit(function(){
        alert($(this).serialize());
    });
});
</script>