我试图传达这样的信息"父母已被警告"单击按钮时显示在窗口警告屏幕中,但到目前为止我无法显示该消息。
JS:
var thirtyMinDelayButton = document.querySelector("30-minute-delayed-button");
var hourDelayButton = document.querySelector("hour-delayed-button");
var cancelledButton = document.querySelector("cancelled-button");
/*
* event listeners
*/
thirtyMinDelayButton.onclick = function() {
window.alert("Parents have been alerted");
};
HTML:
<article id="contentstart">
<h2>Football</h2>
<p>Click a button below to update the schedule.</p>
<div class="changes">
<p class="30-minute-delayed-button">30 Minute Delay</p>
<p class="hour-delayed-button">hour Delay</p>
<p class="cancelled-button">Cancelled</p>
</div>
</article>
为什么这条消息没有显示,因为根据我对JS的理解,它应该有效。
答案 0 :(得分:0)
var thirtyMinDelayButton = document.querySelector(".30-minute-delayed-button");
我快速浏览了一下Document.queryselector Mozilla开发者网站,看起来不错,我能看到的只是课程名称之前的一段时间?
答案 1 :(得分:0)
如果您想对这些元素执行任何操作:
var thirtyMinDelayButton = document.querySelector("30-minute-delayed-button");
var hourDelayButton = document.querySelector("hour-delayed-button");
var cancelledButton = document.querySelector("cancelled-button");
然后将它们更改为:
var thirtyMinDelayButton = document.querySelector(".30-minute-delayed-button");
var hourDelayButton = document.querySelector(".hour-delayed-button");
var cancelledButton = document.querySelector(".cancelled-button");
它们是CSS选择器,因此在使用document.querySelector
时需要在类名前面有一段句子。