function f_validate_form() {
    var form_prod = document.forms["submitForm"]["form_prod"].value;
    var form_model = document.forms["submitForm"]["form_model"].value;
    var form_sit = document.forms["submitForm"]["form_sit"].value;
    var form_capacity = document.forms["submitForm"]["form_capacity"].value;
    var form_transmission = document.forms["submitForm"]["form_transmission"].value;
    var form_year = document.forms["submitForm"]["form_year"].value;
    var form_reg_year = document.forms["submitForm"]["form_reg_year"].value;
    var form_int_color_code = document.forms["submitForm"]["form_int_color_code"].value;
    var form_ext_color_code = document.forms["submitForm"]["form_ext_color_code"].value;
    var form_no_of_owner = document.forms["submitForm"]["form_no_of_owner"].value;
    var form_mileage = document.forms["submitForm"]["form_mileage"].value;
    var form_license_expire_date = document.forms["submitForm"]["form_license_expire_date"].value;
    var form_name = document.forms["submitForm"]["form_name"].value;
    var form_contact_method =  $("input[name='form_contact_method']:checked").val();
    var form_contact_detail = document.forms["submitForm"]["form_contact_detail"].value;
	
		
    var d = new Date();

    if (form_model == null || form_model == "") {
        alert("Please fill in model.");
        return false;
    }
	
	/*
    if (form_sit == null || form_sit == "") {
        alert("Please fill in seat.");
        return false;
    } else if (!f_checkInteger(form_sit)) {
        alert("Please enter a number for seat.");
        return false;
    } else if (f_checkIsGreaterThan(form_sit, 16)) {
        alert("Number of seat should not greater than 16.");
        return false;
    }
	*/
	/*
    if (form_capacity == null || form_capacity == "") {
        alert("Please fill in capacity.");
        return false;
    } else if (!f_checkInteger(form_capacity)) {
        alert("Please enter a number for capacity.");
        return false;
    } else if (f_checkIsGreaterThan(form_capacity, 100000)) {
        alert("Capacity should not greater than 100000cc.");
        return false;
    }
	*/
    if (form_year == null || form_year == "") {
        alert("Please fill in the year of manufacture.");
        return false;
    } else if (!f_checkInteger(form_year)) {
        alert("Please enter a number for the year of manufacture.");
        return false;
    } else if (f_checkIsGreaterThan(form_year, d.getFullYear())) {
        alert("Year of manufacture should not greater than" + d.getFullYear() + ".");
        return false;
    }

    if (form_reg_year == null || form_reg_year == "") {
        alert("Please fill in the year of registration.");
        return false;
    } else if (!f_checkInteger(form_reg_year)) {
        alert("Please enter a number for the year of registration.");
        return false;
    } else if (f_checkIsGreaterThan(form_reg_year, d.getFullYear())) {
    	alert("Year of registration should not greater than" + d.getFullYear() + ".");
        return false;
    }
	/*
    if (form_int_color_code == null || form_int_color_code == "") {
        alert("Please fill in the interior color.");
        return false;
    }

    if (form_ext_color_code == null || form_ext_color_code == "") {
    	alert("Please fill in the exterior color.");
        return false;
    }
	*/
	/*
	if (form_no_of_owner == null || form_no_of_owner == "") {
        //alert("Please fill in the number of owners.");
        //return false;
    } else if (!f_checkInteger(form_no_of_owner)) {
        alert("Please enter a number for the number of owners.");
        return false;
    } else if (f_checkIsGreaterThan(form_no_of_owner, 99)) {
    	alert("Number of owners should not greater than 99.");
        return false;
    }
	*/
	/*
    if (form_mileage == null || form_mileage == "") {
    	alert("Please fill in mileage.");
        return false;
    } else if (!f_checkInteger(form_mileage)) {
    	alert("Please enter a number for mileage.");
        return false;
    }
    */
    /*
    if (form_license_expire_date == null || form_license_expire_date == "") {
    	//alert("Please fill in license expire date.");
        //return false;
    } else if (!f_isDate(form_license_expire_date)){
    	alert("The format of license expire date must be YYYY-MM-DD.");
       return false;
    }
	*/
	
    if (form_name == null || form_name == "") {
    	alert("Please fill in contact person.");
        return false;
    }
	
    if (form_contact_method == 'P') {
        if (form_contact_detail == null || form_contact_detail == '') {
        	alert("Please fill in mobile phone.");
            return false;
        } else if (!f_checkInteger(form_contact_detail)) {
        	alert("Please enter a number for mobile phone.");
            return false;
        } else if (!f_checkLength(form_contact_detail, 0) && !f_checkLength(form_contact_detail, 8)) {
        	alert("Mobile phone should contain 8 digits.");
            return false;
       }
    }  
	
    if (form_contact_method == 'E') {
        if (form_contact_detail == null || form_contact_detail == '') {
        	alert("Please fill in email address.");
            return false;
        } else if (!f_checkIsValidEmail(form_contact_detail)) {
        	alert("Invalid format for email address.");
            return false;  
		}
	}
	
	/*
    if (form_price == null || form_price == "") {
    	alert("Please fill in price.");
        return false;
    } else if (!f_checkInteger(form_price)) {
    	alert("Please enter a number for price.");
        return false;
    }
	*/
    return true;
}