在 Vue 3 的 setup() 函數(shù)中,定義響應(yīng)式屬性主要通過 ref 和 reactive 實(shí)現(xiàn)。1. 使用 ref 創(chuàng)建基本類型的響應(yīng)式屬性,需通過 .value 操作數(shù)據(jù),在模板中自動(dòng)解包;2. 使用 reactive 創(chuàng)建對(duì)象或數(shù)組的響應(yīng)式屬性,直接訪問屬性無(wú)需 .value;3. 選擇 ref 適用于基本類型或需要顯式控制響應(yīng)性的場(chǎng)景,選擇 reactive 適用于對(duì)象或數(shù)組且希望屬性訪問更自然的情況;4. 可結(jié)合 toRefs 避免破壞響應(yīng)性,理解二者差異是關(guān)鍵。
在 Vue 3 的 setup()
函數(shù)中定義響應(yīng)式屬性,主要依賴于 Composition API 提供的幾個(gè)核心函數(shù),比如 ref
和 reactive
。它們是實(shí)現(xiàn)響應(yīng)式數(shù)據(jù)的基礎(chǔ)工具。
使用 ref
創(chuàng)建基本類型的響應(yīng)式屬性
ref
最適合用于創(chuàng)建基本類型(如字符串、數(shù)字、布爾值)的響應(yīng)式屬性。它返回一個(gè)帶有 .value
屬性的對(duì)象,這個(gè) .value
才是你真正操作的數(shù)據(jù)。
import { ref } from 'vue' export default { setup() { const count = ref(0) function increment() { count.value++ } return { count, increment } } }
- 在模板中使用時(shí)不需要加
.value
,Vue 會(huì)自動(dòng)解包。 - 修改值時(shí)一定要記得用
.value
,否則不會(huì)觸發(fā)更新。
小貼士:如果你不小心漏掉了
.value
,Vue 不會(huì)報(bào)錯(cuò),但數(shù)據(jù)也不會(huì)更新,這點(diǎn)容易忽略。
使用 reactive
創(chuàng)建對(duì)象或數(shù)組的響應(yīng)式屬性
當(dāng)你需要讓一個(gè)對(duì)象或數(shù)組變成響應(yīng)式的,推薦使用 reactive
。它直接包裝一個(gè)普通對(duì)象,使其所有嵌套屬性都變?yōu)轫憫?yīng)式。
import { reactive } from 'vue' export default { setup() { const user = reactive({ name: 'Alice', age: 25 }) function updateAge() { user.age++ } return { user, updateAge } } }
- 不像
ref
,你訪問屬性時(shí)不需要加.value
。 - 注意不要給
reactive
傳入基本類型,那樣會(huì)不起作用。
常見問題:如果把
ref
包裝的對(duì)象賦值給reactive
屬性,可能會(huì)導(dǎo)致響應(yīng)性丟失,要小心處理。
何時(shí)選 ref
,何時(shí)選 reactive
?
選擇哪個(gè)要看你的具體場(chǎng)景:
-
? 用
ref
如果:- 數(shù)據(jù)是基本類型。
- 需要在多個(gè)函數(shù)或組件之間傳遞并保持響應(yīng)性。
- 想明確知道哪些變量是響應(yīng)式的(通過
.value
)。
-
? 用
reactive
如果:- 數(shù)據(jù)是一個(gè)對(duì)象或數(shù)組。
- 希望屬性訪問更自然,不帶
.value
。 - 對(duì)象結(jié)構(gòu)比較復(fù)雜,嵌套深。
一個(gè)小技巧:你可以用
toRefs
把reactive
對(duì)象轉(zhuǎn)成一組ref
,方便你在setup()
中返回它們而不破壞響應(yīng)性。
基本上就這些。兩種方式都很實(shí)用,關(guān)鍵在于理解它們適用的場(chǎng)景和差異。
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