javascript - CSS 未捕获类型错误 : Cannot read property 'setAttribute' of null

Question

我正在尝试将 margin-top:10px 分配给 id download-csv

这是 html 和 javascrpit:

<span style="display: inline;"  id="download-csv"><input type="submit"   id="csv_download"  value="Download"></span>;



JavaScript :
         var download_csv=document.getElementById("download-csv");
if(count_layer==1)
        download_csv.setAttribute("style","margin-top:10px");
}else{
       download_csv.setAttribute("style","margin-top:20px");

}

它抛出错误 TypeError:无法读取 null 的属性“setAttribute”

Answer 1

您需要确保在 JS 代码访问这些元素之前加载标记。

另外，你不能给 inline 元素 margin，设置 display style 属性 as 内联显示。

var download_csv = document.getElementById("download-csv");
var count_layer = 1;
if (count_layer == 1) {
  download_csv.style.marginTop = "10px";
} else {
  download_csv.style.marginTop = "50px";
}

<span style="display: inline-block;" id="download-csv">
   <input type="submit"   id="csv_download"  value="Download">
</span>