简单的javascript函数未定义错误

Question

Simply put, I keep getting a Uncaught ReferenceError stating openSideBar is not defined. 简而言之，我不断收到Uncaught ReferenceError，指出未定义openSideBar。 I cannot figure out why. 我不知道为什么。

<head>
 <script>
   document.getElementById('openSideBarButton').addEventListener ("click", openSideBar);

   function openSideBar() {
      document.getElementById('sideBar').style.width "100%";
   }

   function closeSideBar() {
      document.getElementById('sideBar').style.width "0%";
   }

  </script>
</head>

Answer 1

Your script is in the <head> section of the page and attempts to document.getElementById('openSideBarButton') , but that element doesn't exist that early in the page. 您的脚本位于页面的<head>部分，并尝试document.getElementById('openSideBarButton') ，但是该元素在页面的早期并不存在。

Move your script somewhere on the page after the button so that the button exists before your script runs. 在按钮之后将脚本移动到页面上的某个位置，以便该按钮在脚本运行之前就存在。

Side note: You are also missing equals signs in each of your functions. 旁注：您还缺少每个功能中的等号。

Working version: 工作版本：

 <script>
   document.getElementById('openSideBarButton').addEventListener ("click", openSideBar);

   function openSideBar() {
      document.getElementById('sideBar').style.width = "100%";
   }

   function closeSideBar() {
      document.getElementById('sideBar').style.width = "0%";
   }

  </script>
</body>

Notice that it is right before the closing </body> tag instead of in the head section of the page. 请注意，它恰好在结束</body>标记之前，而不是在页面的头部。

简单的javascript函数未定义错误

问题描述

1 个解决方案

解决方案1
0 2016-10-29 20:02:23

简单的javascript函数未定义错误

问题描述

1 个解决方案

解决方案1 0 2016-10-29 20:02:23

解决方案1
0 2016-10-29 20:02:23