javascript - 如何避免在使用 $filter 后更新原始数组？

Question

请看下面的代码:

var fieldsControls = $filter('filter')(vm.FieldsControls, { FieldId: id });

            for (var i = 0; i < fieldsControls.length; i++)
            {
                if (fieldsControls[i].ControlType == "DropDown") {
                    fieldsControls[i].Options = $filter('filter')(vm.Options, { type: fieldsControls[i].type });
                }
            }
            return fieldsControls;

返回后(甚至在 for 循环后)我观察到原始数组“vm.FieldsControls”正在更新为新的 Options 值。但是，这不应该只更改新的数组 fieldControls 吗？

Answer 1

首先准备数组的深拷贝。这是代码:

     var copy = angular.copy(vm.FieldsControls);

     var fieldsControls = $filter('filter')(copy, { FieldId: id });

        for (var i = 0; i < fieldsControls.length; i++)
        {
            if (fieldsControls[i].ControlType == "DropDown") {
                fieldsControls[i].Options = $filter('filter')(vm.Options, { type: fieldsControls[i].type });
            }
        }
        return fieldsControls;