點擊按鈕，段落沒有變色，我無法理解這背后的原因。<button onclick="changeBackGroundOfPs('#firstDiv');">Change backgrounds of p under a given element known by id</button> <br><div id="firstDiv"> <p>First paragraph.</p> <p>Second paragraph.</p></div>function changeBackGroundOfPs(id ) { var paragraphs = document.querySelectorAll(id p); // Another way to iterate on all elements in a collection for (var i = 0; i < paragraphs.length; i++ ) { paragraphs[i].style.backgroundColor = "lightGreen"; }}為什么這可以在查詢選擇器（document.querySelectorAll（“#” + id + “ p”）中添加分號的情況下工作）;.<button onclick="changeBackGroundOfPs('firstDiv');">Change backgrounds of p under a given element known by id</button> <br><div id="firstDiv"> <p>First paragraph.</p> <p>Second paragraph.</p></div>function changeBackGroundOfPs(id) { var paragraphs = document.querySelectorAll("#" + id + " p"); // Another way to iterate on all elements in a collection for (var i = 0; i < paragraphs.length; i++ ) { paragraphs[i].style.backgroundColor = "lightGreen"; }}
無法更改按鈕單擊上的文本顏色
長風秋雁
2022-09-02 21:39:14
