function form_check(form_id) {
	var element_count;
	var title; 
	var value; 
	var regexp; 
	var checked = true;
    var  error_mesg = null;
	if (form_id) {
		if (document.getElementById(form_id)) {
			element_count = document.getElementById(form_id).elements.length
			for(var i=0; i< element_count; i++) {
				title = document.getElementById(form_id).elements[i].title;
				value = document.getElementById(form_id).elements[i].value;
				switch (title) {
					case 'number' :
						regexp = /[-+A_Z0-9]+/; 
						checked = regexp.test(value);
						break;
					case 'email' :
						regexp = /^[_\.0-9A-Za-z-]+@[_\.0-9a-z-]+[a-z]+$/; 
						checked = regexp.test(value);
						break;
					case 'string' :
						if (value.length <= 0) {
							checked = false;
						}
						break;
					case 'text' :
						if (value.length <= 0) {
							checked = false;
						}
						break;
					case 'select' :
						if (value.length <= 0) {
							checked = false;
						}
						break;
					case 'picture' :
					default: break;
				}
				if (checked == false) {
					if (error_mesg == null) 
						alert("Please fill all required fields.");
					else
						alert(error_mesg);
					document.getElementById(form_id).elements[i].focus();
					return checked;
				}
			}
		} else
			alert("No form id="+form_id+" found in document.");
	} else
		alert("No form id geted.");
	return checked;
}