javascript - 如何使用javascript for循环按类名获取元素宽度？

Question

当我测试时，它会提示 blank value 和 30px我想获得警报 400px 和 30px 我该怎么做？

.div_cover_threads_image{
  width: 400px;
}

<div class="div_cover_threads_image">
test
</div>

<div class="div_cover_threads_image" style="width: 30px;">
test
</div>


<script>     
var div_cover_threads_image_Elem = document.getElementsByClassName('div_cover_threads_image');
for(var i=0, len=div_cover_threads_image_Elem.length; i<len; i++)
{
  	alert(div_cover_threads_image_Elem[i].style.width);
}  
</script>

Answer 1

当你标记 jQuery 时，这将返回元素的宽度，即使没有明确定义宽度也是如此:

.div_cover_threads_image{
  width: 400px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="div_cover_threads_image">
test
</div>

<div class="div_cover_threads_image" style="width: 30px;">
test
</div>


<script>     
var div_cover_threads_image_Elem = document.getElementsByClassName('div_cover_threads_image');
for(var i=0, len=div_cover_threads_image_Elem.length; i<len; i++)
{
  	alert($(div_cover_threads_image_Elem[i]).width());
}  
</script>