//the following function is used to validate add accessory to cart, make sure customer check at least one accessory 
function validate_add_to_cart_multiple(form){
	var checkbox_checked = 0;
	var total_checkbox = document.getElementsByName('f_AccessoryID[]').length;
		
	for (var i= 0; i < total_checkbox; i++){
		if (document.getElementById('f_CheckBox[' + i + ']').checked){ 
			checkbox_checked = checkbox_checked + 1; 
		}
	}
	
	if (checkbox_checked >= 1 ){
		return true
	} else {
		alert('ERROR ! \n\n- Select at least one Accessory.\n');	
		return false
	}
	
}