You're only running your check code on the submit click, you need to run it for other events you're interested in such as the textarea or file changing
$('#form').submit(function() {
return validate();
});
$('#txtarea').keyup(function(){validate();});
$('#file').change(function(){validate();});
function validate()
{
if ($.trim($("#txtarea").val()) !== "" || $.trim($("#file").val()) !== "") {
$("#submit").html('proceed');
return true;
} else {
$("#submit").html('Not proceed');
return false;
}
}