這是最后一篇文章了，我所需要的知識到這里都結束了，書本剩余的內容都是一些最佳實踐。應該在實踐中遇到問題了再回來學習。
A JavaScript Image Gallery
- childNodes
- nodeType
- nodeValue
- firstChild
- lastChild
Image Gallery
gallery.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title>Image Galerry</title>
<script type="text/javascript" src="showPic.js"></script>
</head>
<body>
<h1>Snapshots</h1>
<ul>
<li>
<a title="A fireworks display" onclick = "showPic(this); return false;"> Fireworks</a>
</li>
<li>
<a title="A cup of black coffee" onclick = "showPic(this); return false;"> Coffee</a>
</li>
<li>
<a title="A red, red rose" onclick = "showPic(this); return false;">Rose</a>
</li>
<li>
<a title="The famous clock" onclick = "showPic(this); return false;"> Big Ben</a>
</li>
</ul>
<img id="placeholder" src="https://dummyimage.com/600x400/789/FFF&text=placeholder" alt="my image gallery" />
</body>
</html>
showPic.js
function showPic(whichpic) {
var source = whichpic.getAttribute("href");
var placeholder = document.getElementById("placeholder");
placeholder.setAttribute("src", source);
}
childNodes
function countBodyChildren() {
var body_element = document.getElementsByTagName("body")[0];
console.log(body_element.childNodes.length);
}
window.onload = countBodyChildren;
nodeType property
var body_element = document.getElementsByTagName("body")[0];
console.log('body_element.nodeType = ' + body_element.nodeType);
- Element nodes have a nodeType value of 1.
- Attribute nodes have a nodeType value of 2.
- Text nodes have a nodeType value of 3.
Adding a description in the markup
gallery.html 添加一個標簽
<p id="description">Choose an image.</p>
修改 showPic.js 的 showPic 方法
function showPic(whichpic) {
// ...
var text = whichpic.getAttribute("title");
var description = document.getElementById("description");
description.firstChild.nodeValue = text;
}