按类获取元素 - JavaScript

Question

如何通过classname获取Class中的第一个或最后一个<p>元素？no jQuery

<div class ="demo">
  <p>some text</p>
  <p>some other text</p>
</div>

Answer 1

getElementsByClassName()方法返回文档中具有指定类名的所有元素的集合，作为NodeList对象。

＆＃13;

＆＃13;

var firstChild = document.getElementsByClassName('demo')[0].children[0];
console.log(firstChild)

＆＃13;

<div class ="demo">
  <p>some text</p>
  <p>some other text</p>
</div>

＆＃13;

＆＃13;

＆＃13;

Answer 2

var ele = document.querySelector('.demo')
console.log(ele.firstElementChild)//first element of class
console.log(ele.lastElementChild)//last element of class

<div class ="demo">
  <p>some text</p>
  <p>some other text</p>
</div>