本文探讨了 Vue 3 中 watch 和 watchEffect 之间的差异,重点介绍了它们的用法和功能。 watch 是一个立即模式反应函数,在组件安装和数据更改时调用,而 watchEffect 是一个惰性模式 r
Vue3 引入了一个新的反应性 API包括两个新函数:watch
和 watchEffect
。这两个函数都允许您跟踪 Vue 组件中反应状态的更改,但它们以不同的方式实现。 watch
和 watchEffect
函数之间的主要区别是:watch
and watchEffect
. Both of these functions allow you to track changes to reactive state in your Vue components, but they do so in different ways. The main distinctions between the watch
and watchEffect
functions are:
watch
uses immediate mode reactive function, which means that the watcher function is called immediately after the component is mounted and whenever the observed data changes.watchEffect
uses lazy mode reactive function which means that the effect function is only called when the observed data changes.watch
The watch
function accepts two arguments:
<code>// Watch a single property watch('count', () => { console.log(`The count has changed to ${count}`); }); // Watch multiple properties watch(['count', 'message'], () => { console.log(`The count or message has changed.`); });</code>
watchEffect
The watchEffect
function accepts only one argument:
<code>watchEffect(() => { console.log(`The count is now ${count}`); });</code>
You should use watch
when you need to perform an action when the value of a specific reactive property changes. For example, you might use watch
to update the UI when the value of a form input changes.
You should use watchEffect
when you need to perform an action that depends on multiple reactive properties. For example, you might use watchEffect
to calculate the total price of a product based on the quantity and unit price of the product.
In general, watchEffect
is more efficient than watch
because it only calls the effect function when the observed data changes. However, watch
watch
使用立即模式反应函数 strong>,这意味着在组件安装后以及每当观察到的数据发生变化时立即调用观察者函数。
watchEffect
使用惰性模式反应函数 这意味着只有当观察到的数据发生变化时才会调用效果函数。watch
函数接受两个参数:🎜watchEffect
函数仅接受一个参数:🎜watch
当您需要在特定反应性属性的值发生变化时执行操作时。例如,当表单输入的值发生变化时,您可以使用 watch
来更新 UI。🎜🎜当您需要执行依赖于以下内容的操作时,您应该使用 watchEffect
多种反应特性。例如,您可以使用 watchEffect
根据商品的数量和单价来计算商品的总价。🎜🎜一般来说,watchEffect
比watch
因为它只在观察到的数据发生变化时调用效果函数。然而,watch
更简洁,更容易阅读和理解。🎜以上是Vue3中watch和watchEffect区别和用法的详细内容。更多信息请关注PHP中文网其他相关文章!