在上一个例子中我们看到状态对 重新赋值 做出了响应，状态也可以对 修改 做出响应，我们称之为 深度响应

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

接下来是一个深度响应的例子，首先定义个变量numbers并使用$state符文（rune）定义它的值为响应数组。

Make numbers a reactive array:

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

现在我们改变下数组...

Now, when we change the array...

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

你可以看到组件也更新了。更🐂X的是使用数组的push方法修改数组，响应依然有效。

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

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

深度状态响应使用proxies实现.

Deep reactivity is implemented using proxies, and mutations to the proxy do not affect the original object.