ref用於創(chuàng)建可響應(yīng)式引用，必須先給出明確答案：ref是Vue 3 Composition API中用於創(chuàng)建可響應(yīng)式引用的核心函數(shù)，適用於管理響應(yīng)式狀態(tài)和DOM引用；①使用ref()可使基本類型值或?qū)ο缶邆漤憫?yīng)性，需通過.value讀寫；②在模板中自動解包，無需.value；③可用於獲取DOM元素或子組件實例，掛載後通過.value訪問；④與reactive、computed等API協(xié)同工作，是setup()中實現(xiàn)響應(yīng)式的首選方式。

In Vue 3, ref is a function used to create a reactive reference to a value. It's one of the core pieces of Vue's Composition API and helps you make primitive values (like strings, numbers, booleans) or even objects reactive — meaning Vue can track changes to them and update the UI when they change.

Why use ref ?

When you want to make a variable reactive inside a setup() function or a <script setup></script> block, you wrap it in ref() . Without it, changing the variable won't trigger a view update.

 import { ref } from 'vue'

const count = ref(0)
count.value = 1 // You must access .value to get/set the value

Even though ref is mostly used for primitives, it works with objects too (though reactive() is often preferred for complex objects).

How ref works in templates

One nice thing in Vue 3 is that you don't need .value in templates — Vue automatically unwraps it.

 <script setup>
import { ref } from &#39;vue&#39;

const name = ref(&#39;Alice&#39;)
const count = ref(0)

function increment() {
  count.value  
}
</script>

<template>
  <p>{{ name }}</p> <!-- No .value needed -->
  <p>{{ count }}</p> <!-- Automatically unwrapped -->
  <button @click="increment">Add</button>
</template>

Refs for DOM access

Another common use of ref is to directly access DOM elements or child components.

 <script setup>
import { ref, onMounted } from &#39;vue&#39;

const inputEl = ref(null)

onMounted(() => {
  inputEl.value.focus() // Focus the input when mounted
})
</script>

<template>
  <input ref="inputEl" type="text" />
</template>

Here, ref("inputEl") binds the actual DOM element to inputEl.value when rendered.

? Note: The ref is null before the component is mounted.

Key points about ref

• Use ref() for reactive primitive values .
• Always use .value inside JavaScript to read or assign.
• No need for .value in templates — it's auto-unwrapped.
• Can be used to access DOM elements or child component instances .
• Works seamlessly with reactive() , computed , and other Composition API tools.

So, in short:
ref creates a reactive container for a value — essential for reactivity in the Composition API, whether you're managing state or grabbing a reference to an element.

Basically, if you're using setup() and want a variable to be reactive, start with ref() .

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