javascript - 如何通过javascript获取元素宽度

Question

查找宽度的 JavaScript 代码是什么？

(我想要获取宽度 .FixedBox 没有 jquery 的 javascript，但我的代码不起作用。)

alert(document.getElementsByClassName('FixedBox').offsetWidth);

<div class="FixedBox">
    The HTMLElement.offsetWidth read-only property returns the layout width of an element. Typically, an element's offsetWidth is a measurement which includes the element borders, the element horizontal padding, the element vertical scrollbar (if present, if rendered) and the element CSS width.
</div>

Answer 1

Document.getElementsByClassName() 返回 NodeList 你需要从集合中获取元素才能得到 offsetWidth 属性。还将它们放在窗口加载回调中，以便仅在加载元素后执行。

window.onload = function() {
  var ele = document.getElementsByClassName('FixedBox');
  alert(ele.length ? ele[0].offsetWidth : 'no elements with the class');
}

<div class="FixedBox">
  The HTMLElement.offsetWidth read-only property returns the layout width of an element. Typically, an element's offsetWidth is a measurement which includes the element borders, the element horizontal padding, the element vertical scrollbar (if present,
  if rendered) and the element CSS width.
</div>