JavaScript 操作 CSS 的方法主要有四種:一是通過 element.style 修改內(nèi)聯(lián)樣式,使用駝峰命名設(shè)置樣式屬性,如 box.style.backgroundColor;二是使用 classList 添加、移除或切換類名,實現(xiàn)更易維護的狀態(tài)控制;三是通過 window.getComputedStyle 獲取元素最終應用的樣式,該對象為只讀;四是可以動態(tài)創(chuàng)建 style 元素或使用 insertRule 向樣式表中插入新規(guī)則,適用于動態(tài)主題等場景。
操作 CSS 樣式是 JavaScript 中非常常見且實用的功能,尤其是在實現(xiàn)動態(tài)網(wǎng)頁效果時。通過 JS 可以直接修改元素的樣式、添加或移除類名,甚至動態(tài)創(chuàng)建和插入 CSS 規(guī)則。下面是一些常用方法,幫助你更好地用 JS 控制 CSS。

修改元素內(nèi)聯(lián)樣式
最直接的方式就是通過 element.style
來設(shè)置內(nèi)聯(lián)樣式。這種方式適合需要動態(tài)計算樣式的場景,但不太適合大量樣式控制。

const box = document.getElementById('box'); box.style.width = '200px'; box.style.height = '100px'; box.style.backgroundColor = 'red';
注意:
- 屬性名要用駝峰寫法(如
backgroundColor
而不是background-color
)。 - 設(shè)置的是內(nèi)聯(lián)樣式,優(yōu)先級較高,可能會覆蓋 CSS 文件中的規(guī)則。
使用 classList 操作類名
更推薦的方式是通過操作類名來改變樣式,這樣可以把樣式邏輯保留在 CSS 中,JS 只負責切換狀態(tài)。

const element = document.querySelector('.btn'); element.classList.add('active'); // 添加類 element.classList.remove('disabled'); // 移除類 element.classList.toggle('highlight'); // 切換類
適用場景:
- 實現(xiàn)按鈕點擊高亮
- 表單驗證后的錯誤提示樣式切換
- 動態(tài)顯示/隱藏內(nèi)容
獲取最終樣式(考慮繼承和層疊)
如果你想獲取某個元素在頁面中實際應用的樣式(比如從 CSS 文件中繼承來的),可以使用 window.getComputedStyle()
。
const element = document.querySelector('#text'); const style = window.getComputedStyle(element); console.log(style.fontSize); // 輸出類似 "16px"
這個方法返回的是只讀對象,不能用來修改樣式,但它能準確反映元素當前顯示的樣式。
動態(tài)創(chuàng)建和插入 CSS 規(guī)則
如果你需要運行時動態(tài)生成一些樣式規(guī)則,可以通過 JS 創(chuàng)建 <style>
元素并插入到頁面中。
const style = document.createElement('style'); style.textContent = ` .highlight { background-color: yellow; font-weight: bold; } `; document.head.appendChild(style);
或者更靈活地添加規(guī)則到現(xiàn)有樣式表中:
const sheet = document.styleSheets[0]; sheet.insertRule('.new-class { color: blue; }', sheet.cssRules.length);
這種方式適用于主題切換、用戶自定義樣式等高級用途。
基本上就這些。你可以根據(jù)具體需求選擇合適的方法:簡單樣式變動用 style
,復雜狀態(tài)切換用 classList
,獲取真實樣式用 getComputedStyle
,動態(tài)樣式注入可以用創(chuàng)建 <style>
或 insertRule
。
The above is the detailed content of How to manipulate CSS styles with js?. For more information, please follow other related articles on the PHP Chinese website!

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