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Table of Contents
適合場景:
v-show 是“切換 CSS 的 display 屬性”
總結(jié)一下怎么選
Home Web Front-end Vue.js When should I use v-if versus v-show?

When should I use v-if versus v-show?

Jul 02, 2025 am 12:45 AM

v-if 和 v-show 的選擇取決于性能和行為需求。1. v-if 是“有條件地渲染”,條件為假時元素不會存在于 DOM 中,適合條件很少變化的內(nèi)容,優(yōu)點是節(jié)省資源,缺點是頻繁切換影響性能;2. v-show 通過切換 CSS display 屬性控制顯示,元素始終在 DOM 中,適合頻繁切換的場景,優(yōu)點是切換快,缺點是占用額外內(nèi)存??偨Y(jié):首次加載不顯示優(yōu)先用 v-if,頻繁切換則用 v-show,也可結(jié)合使用以達(dá)到更精細(xì)的控制。

在 Vue 中,v-ifv-show 都是用來控制元素是否顯示的指令,但它們的工作方式完全不同。選擇用哪個,關(guān)鍵在于你對性能和行為的需求。

v-if 是“有條件地渲染”

當(dāng)你使用 v-if 時,Vue 會根據(jù)條件判斷是否將該元素插入到 DOM 中。如果條件為假,這個元素根本不會存在 DOM 里。

適合場景:

  • 條件很少變化的內(nèi)容,比如頁面初始化時根據(jù)權(quán)限判斷是否顯示某個按鈕。
  • 不常切換顯示狀態(tài)的部分,因為頻繁銷毀和重建組件會有一定性能開銷。

? 優(yōu)點:不渲染的時候完全不在 DOM 中,節(jié)省資源。
? 缺點:切換頻繁時會影響性能。

舉個例子:

<div v-if="isLoggedIn">歡迎回來!</div>

如果 isLoggedInfalse,這段 HTML 根本不會出現(xiàn)在頁面上。


v-show 是“切換 CSS 的 display 屬性”

v-show 則是通過切換元素的 CSS display 屬性來控制顯示與隱藏。不管條件如何,元素始終會被渲染并保留在 DOM 中。

適合場景:

  • 需要頻繁切換顯示狀態(tài)的元素,比如一個彈出菜單或選項卡內(nèi)容。
  • 對首屏加載速度要求不高,但交互頻繁的功能模塊。

? 優(yōu)點:切換速度快,沒有創(chuàng)建/銷毀組件的開銷。
? 缺點:即使隱藏了也仍然在 DOM 中,可能占用額外內(nèi)存。

例如:

<div v-show="isVisible">我是可以快速切換的區(qū)域</div>

無論 isVisibletrue 還是 false,這個 div 都會在頁面中,只是通過 display: none 來隱藏。


總結(jié)一下怎么選

  • 如果你的元素幾乎不動,或者首次加載不需要顯示,優(yōu)先用 v-if
  • 如果你需要頻繁切換顯示狀態(tài),那 v-show 更合適。
  • 想更精細(xì)控制?也可以結(jié)合兩者使用,比如先用 v-if 控制是否渲染,再用 v-show 控制后續(xù)切換。

基本上就這些。不復(fù)雜但容易忽略的是:理解背后的機(jī)制比記住規(guī)則更重要。

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