javascript - 无法读取 NULL 的属性

Question

我有以下 html 文件，我尝试在其中使用网络 worker 突出显示一些代码:

<link rel="stylesheet" href="./highlight/styles/default.css">
<script src="./highlight/highlight.pack.js"></script>

<script src="http://code.jquery.com/jquery-1.11.0.min.js"></script>
<script>

	if (typeof(Worker) !== "undefined") {

    	addEventListener('load', function() {
			var code = document.querySelector('#code');
			var worker = new Worker('worker.js');
			worker.onmessage = function(event) { code.innerHTML = event.data; }
			worker.postMessage(code.textContent);
		})
	
	} else {
	}


</script>


<pre><code>
// This is a generated file with many packages
`ifdef MACRO_1
`else
package pkg_1;
  typedef logic [1:0] t;
  typedef enum t {
      IDLE = 2'd0
    , ARMED = 2'd1
    , WRITE = 2'd2
    , BUSY = 2'd3
  } e;
</code></pre>

但我收到一条错误消息:Uncaught TypeError: Cannot read property 'textContent' of null (worker.postMessage(content.textContent));

有解决办法吗？

Answer 1

在代码元素上添加 id="code"属性:https://jsbin.com/daqijafoca/edit?html,output

<link rel="stylesheet" href="./highlight/styles/default.css">
<script src="./highlight/highlight.pack.js"></script>

<script src="http://code.jquery.com/jquery-1.11.0.min.js"></script>
<script>

    if (typeof(Worker) !== "undefined") {

        addEventListener('load', function() {
            var code = document.querySelector('#code');
            var worker = new Worker('worker.js');
            worker.onmessage = function(event) { code.innerHTML = event.data; }
            worker.postMessage(code.textContent);
        })

    } else {
    }


</script>


<pre><code id="code">
// This is a generated file with many packages
`ifdef MACRO_1
`else
package pkg_1;
  typedef logic [1:0] t;
  typedef enum t {
      IDLE = 2'd0
    , ARMED = 2'd1
    , WRITE = 2'd2
    , BUSY = 2'd3
  } e;
</code></pre>