JS不改HTML任何程式碼就達到動態效果

findumars發表於2013-07-01
JSHTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN"
"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml: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>
    <link rel="stylesheet" href="styles/layout.css" type="text/css" media="screen" />
</head>
<body>
  <h1>Snapshots</h1>
  <ul id="imagegallery">
    <li>
      <a href="images/fireworks.jpg" title="A fireworks display">
        <img src="images/thumbnail_fireworks.jpg" alt="Fireworks" />
      </a>
    </li>
    <li>
      <a href="images/coffee.jpg" title="A cup of black coffee" >
        <img src="images/thumbnail_coffee.jpg" alt="Coffee" />
      </a>
    </li>
    <li>
      <a href="images/rose.jpg" title="A red, red rose">
        <img src="images/thumbnail_rose.jpg" alt="Rose" />
      </a>
    </li>
    <li>
      <a href="images/bigben.jpg" title="The famous clock">
        <img src="images/thumbnail_bigben.jpg" alt="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>
showPic.js檔案內容：
function showPic(whichpic) {
  if (!document.getElementById("placeholder")) return true;
  var source = whichpic.getAttribute("href"); // 得到連結屬性
  var placeholder = document.getElementById("placeholder"); // 找到目標元素
  placeholder.setAttribute("src",source); // 更換圖片

  if (!document.getElementById("description")) return false;
  if (whichpic.getAttribute("title")) {
    var text = whichpic.getAttribute("title"); // 得到title屬性
  } else {
    var text = "";
  }
  var description = document.getElementById("description");
  if (description.firstChild.nodeType == 3) {
    description.firstChild.nodeValue = text;  // 更換文字
  }
  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"); // 先找到某一個id的元素
  var links = gallery.getElementsByTagName("a");  // 在此id下找到所有a的元素
  for ( var i=0; i < links.length; i++) { // 對每個a進行分析（掛上onclick事件），這樣做的好處是不用動html裡一行程式碼
    links[i].onclick = function() {
      return showPic(this);
    }
    links[i].onkeypress = links[i].onclick; // 讓 onkeypress 等於 onclick 事件
  }
}

function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      oldonload();
      func();
    }
  }
}

addLoadEvent(prepareGallery); // 自動在檔案載入的時候就執行。

 

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