Home
JS
JS
Tryit: JAVASCRIPT
运行 ❯
×
Change Orientation
Change Theme, Dark/Light
<!DOCTYPE html> <html> <head> </head> <body> <h1>HTMLCollection length Property</h1> <p>一个 p 元素。</p> <p class="myclass">另一个 p 元素。</p> <p class="myclass">第三个 P 元素。</p> <p>点击按钮为所有class="myclass"的元素添加背景色：</p> <button onclick="myFunction()">设置颜色</button> <script> function myFunction() { var x, i; x = document.getElementsByClassName("myclass"); for (i = 0; i < x.length; i++) { x[i].style.backgroundColor = "red"; } } </script> </body> </html>