JavaScript DOM编程艺术第六章代码报错

weixin_43694807 2018-12-11 02:17:29

我把 JavaScript DOM编程艺术第六章里面的一套代码粘到Dreamweaver里面之后，在JS文件里Dreamweaver提示了很多错误/警示。但是明明网页可以正常运行呀，请问大佬是什么原因呀。

这是JS文件显示的错误/警示：

这是JS:



function showPic(whichpic) {

  if (!document.getElementById("placeholder")) return true;

  var source = whichpic.getAttribute("href");

  var placeholder = document.getElementById("placeholder");

  placeholder.setAttribute("src",source);

  if (!document.getElementById("description")) return false;

  if (whichpic.getAttribute("title")) {

    var text = whichpic.getAttribute("title");

  } else {

    var text = "";

  }

  var description = document.getElementById("description");

  if (description.firstChild.nodeType == 3) {

    description.firstChild.nodeValue = text;

  }

  return false;

}



function prepareGallery() {

  if (!document.getElementsByTagName) return false;

  if (!document.getElementById) return false;

  if (!document.getElementById("imagegallery")) return false;

  var gallery = document.getElementById("imagegallery");

  var links = gallery.getElementsByTagName("a");

  for ( var i=0; i < links.length; i++) {

    links[i].onclick = function() {

      return showPic(this);

	}

    links[i].onkeypress = links[i].onclick;

  }

}



function addLoadEvent(func) {

  var oldonload = window.onload;

  if (typeof window.onload != 'function') {

    window.onload = func;

  } else {

    window.onload = function() {

      oldonload();

      func();

    }

  }

}



addLoadEvent(prepareGallery);

这是HTML：



<!DOCTYPE html>

<html lang="en">

<head>

  <meta http-equiv="content-type" content="text/html; charset=utf-8" />

  <title>Image Gallery</title>

	<script type="text/javascript" src="scripts/showPic.js"></script>

</head>

<body>

  <h1>Snapshots</h1>

  <ul id="imagegallery">

    <li>

      <a href="images/fireworks.jpg" title="A fireworks display">Fireworks</a>

    </li>

    <li>

      <a href="images/coffee.jpg" title="A cup of black coffee" >Coffee</a>

    </li>

    <li>

      <a href="images/rose.jpg" title="A red, red rose">Rose</a>

    </li>

    <li>

      <a href="images/bigben.jpg" title="The famous clock">Big Ben</a>

    </li>

  </ul>

  <img id="placeholder" src="images/placeholder.gif" alt="my image gallery" />

  <p id="description">Choose an image.</p>

</body>

</html>