function w3_open() {
document.getElementById("mySidebar").style.display = "block";
document.getElementById("w3-button").style.display = "none"
document.getElementById("w3-buttondos").style.display ="inline-block"
}
function w3_close() {
document.getElementById("mySidebar").style.display = "none";
document.getElementById("w3-buttondos ").style.display = "none"
document.getElementById("w3-button").style.display ="inline-block"
}<button class="w3-button w3-teal" onclick="w3_open()">☰</button>
<button class="w3-buttondos w3-teal" onclick="w3_close()">✖</button>它說我 - > Uncaught TypeError: document.getElementById(...) is null
uj5u.com熱心網友回復：
document.getElementById不以節點為目標，而是以其為目標id=""
<button id="w3-button" class="w3-button w3-teal" onclick="w3_open()">☰</button>
要按元素定位元素，class您可以使用document.querySelector
document.querySelector(".w3-button")
uj5u.com熱心網友回復：
如果您正在使用，document.getElementById()那么您必須在 html 元素中宣告 id 屬性。喜歡：id="w3-button"
function w3_open() {
document.getElementById("mySidebar").style.display = "block";
document.getElementById("w3-button").style.display = "none"
document.getElementById("w3-buttondos").style.display ="inline-block"
}
function w3_close() {
document.getElementById("mySidebar").style.display = "none";
document.getElementById("w3-buttondos").style.display = "none"
document.getElementById("w3-button").style.display ="inline-block"
}<button id="w3-button" class="w3-button w3-teal" onclick="w3_open()" hidden>☰</button>
<button id="w3-buttondos" class="w3-buttondos w3-teal" onclick="w3_close()">✖</button>
<div id="mySidebar">
My Sidebar
</div>轉載請註明出處，本文鏈接：https://www.uj5u.com/houduan/424599.html
標籤：javascript html css