JavaScript基于DOM操作实现查找、修改HTML元素的内容及属性的方法

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta http-equiv="Content-Language" content="zh-cn" />
<title>Javascript HTML DOM</title>
<head>
 <style type="text/css">
  body {background-color:#eeeeee}
 </style>
</head>
<body>
 <h3>(一)通过 id 查找 HTML 元素</h3>
 <p id = "hw">Hello world!</p>
 <script>
  x = document.getElementById("hw");
  document.write('<p>id="hw"的段落的文本是：'+x.innerHTML+'</p>');
 </script>
 <button onclick = "setCurrentTime()">将id="hw"的文字改为当前时间</button>
 <script>
  function setCurrentTime(){
   x = document.getElementById("hw");
   x.innerHTML = Date()
  }
 </script>
 <h3>(二)通过 标签名 查找 HTML 元素</h3>
 <div id = "mainDiv">
  <p>This is a paragragph.</p>
  <p>This is another paragragph.</p>
  <p>Yes you're right! This is also paragragph.</p>
 </div>
 <script>
  xx = document.getElementById("mainDiv");
  tagContents = xx.getElementsByTagName("p");
  document.write("<p>使用Javascript查找id为mainDiv下的p标签的内容</p>");
  for(i=0;;i++){
   var tag = tagContents[i]
   if(tag!=null){
    document.write("<p>"+tag.innerHTML+"</p>")
   }else{
    document.write("<p>共有"+i+"条内容</p>")
    break;
   }
  }
 </script>
 <h3>(三)修改 HTML 的属性</h3>
 <img id = "bol" src = "images/eg_bulboff.gif" width="70px" height="120px"/>
 <p><button onclick = "changeSrc()">改变图片资源</button></p>
 <script>
  function changeSrc(){
   x = document.getElementById("bol");
   if (x.src.match("eg_bulboff.gif")){
    x.src = "images/eg_bulbon.gif"
   }else{
    x.src = "images/eg_bulboff.gif"
   }
  }
 </script>
 <h3>(四)修改 CSS 样式</h3>
 <p>
  <span id = "para_1">This is a test paragraph.</span>
  <button onclick="changeTextColor()">改变文字颜色</button>
 </p>
 <p>
  <span id = "para_2">This is another paragraph.
  <button onclick="changeTextFont()">改变字体</button>
 </p>
 <p>
  <span id = "para_3">This is HELLO WORLD.</span>
  <button onclick="changeTextSize()">改变字号</button>
 </p>
 <p>
  <button onclick="changeVisibility()">显示/隐藏</button>
  <span id = "para_4">示例文字</span>
 </p>
 <script>
  function changeTextColor(){
   ele_1 = document.getElementById("para_1");
   ele_1.style.color = "red";
  }
  function changeTextFont(){
   ele_2 = document.getElementById("para_2");
   ele_2.style.fontFamily = "Arial";
  }
  function changeTextSize(){
   ele_3 = document.getElementById("para_3");
   ele_3.style.fontSize = "larger";
  }
  document.getElementById("para_4").style.visibility = "visible"
  function changeVisibility(){
   ele_4 = document.getElementById("para_4");
   if(ele_4.style.visibility.match("visible")){
    ele_4.style.visibility = "hidden"
   }else{
    ele_4.style.visibility = "visible"
   }
  }
 </script>
</body>
</html>