Question

var arr = [{id: 1, name: 'John'}, {id: 2, name: 'Mike'}];

var member = arr[0];

arr.splice(0, 1);

console.log(member);

Answer 1

您可以继续访问它，因为您仍然对其具有引用。它不再存在于数组中，但仍然存在。它会一直存在，直到所有对它的引用都被删除为止，并且一旦存在，就可以进行垃圾回收了。

之后：

var arr = [{id: 1, name: 'John'}, {id: 2, name: 'Mike'}];

您的内存中有类似的内容（省略了一些详细信息）：

                  +−−−−−−−−−−−−+
arr:Ref4875−−−−−−>|   (array)  |
                  +−−−−−−−−−−−−+      +−−−−−−−−−−−−−−+
                  | 0: Ref8612 |−−−−−>|   (object)   |
                  | 1: Ref4631 |−−+   +−−−−−−−−−−−−−−+
                  +−−−−−−−−−−−−+  |   | id: 1        |
                                  |   | name: "John" |
                                  |   +−−−−−−−−−−−−−−+
                                  |
                                  |   +−−−−−−−−−−−−−−+
                                  +−−>|   (object)   |
                                      +−−−−−−−−−−−−−−+
                                      | id: 1        |
                                      | name: "John" |
                                      +−−−−−−−−−−−−−−+

（“ Ref1234”值称为对象引用。您永远不会看到它们的实际值，但是可以将它们视为JavaScript引擎用来查找对象在内存中的位置的数字）

此后：

var member = arr[0];

member和数组均引用对象，如下所示：

member:Ref8612−−−−−−−−−−−−−−−−−−−−−+
                  +−−−−−−−−−−−−+   |
arr:Ref4875−−−−−−>|   (array)  |   |
                  +−−−−−−−−−−−−+   |  +−−−−−−−−−−−−−−+
                  | 0: Ref8612 |−−−+−>|   (object)   |
                  | 1: Ref4631 |−−+   +−−−−−−−−−−−−−−+
                  +−−−−−−−−−−−−+  |   | id: 1        |
                                  |   | name: "John" |
                                  |   +−−−−−−−−−−−−−−+
                                  |
                                  |   +−−−−−−−−−−−−−−+
                                  +−−>|   (object)   |
                                      +−−−−−−−−−−−−−−+
                                      | id: 1        |
                                      | name: "John" |
                                      +−−−−−−−−−−−−−−+

之后：

arr.splice(0, 1);

该数组不再有对其的引用，但是member仍然有：

                                      +−−−−−−−−−−−−−−+
member:Ref8612−−−−−−−−−−−−−−−−−−−−−−−>|   (object)   |
                  +−−−−−−−−−−−−+      +−−−−−−−−−−−−−−+
arr:Ref4875−−−−−−>|   (array)  |      | id: 1        |
                  +−−−−−−−−−−−−+      | name: "John" |
                  | 0: Ref4631 |−−+   +−−−−−−−−−−−−−−+
                  +−−−−−−−−−−−−+  | 
                                  | 
                                  | 
                                  | 
                                  |
                                  |   +−−−−−−−−−−−−−−+
                                  +−−>|   (object)   |
                                      +−−−−−−−−−−−−−−+
                                      | id: 1        |
                                      | name: "John" |
                                      +−−−−−−−−−−−−−−+

从数组中删除该成员时，我们如何访问它？

1 个答案: