label-to-placeholder.js

$('form :input').each(function(index, elem) {
    var eId = $(elem).attr('id');
    var label = null;
    if (eId && (label = $(elem).parents('form').find('label[for='+eId+']')).length === 1) {
        $(elem).attr('placeholder', $(label).html());
        $(label).addClass('hide');
    }
});