正如我们在上一个练习中看到的，状态会对重新分配做出反应。但它也会对突变做出反应 - 我们称之为深度反应。

¥As we saw in the previous exercise, state reacts to reassignments. But it also reacts to mutations — we call this deep reactivity.

将 numbers 设为反应数组：

¥Make numbers a reactive array:

let numbers = $state([1, 2, 3, 4]);

现在，当我们更改数组时……

¥Now, when we change the array...

function addNumber() {
	numbers[numbers.length] = numbers.length + 1;
}

...组件更新。或者更好的是，我们可以将 push 改为数组：

¥...the component updates. Or better still, we can push to the array instead:

function addNumber() {
	numbers.push(numbers.length + 1);
}

使用 proxies 实现深度反应性，对代理的修改不会影响原始对象。

¥[!NOTE] Deep reactivity is implemented using proxies, and mutations to the proxy do not affect the original object.