Object notation for DOM elements
In following example, there is array-like object for DOM elements and there is one thing which is unclear to me.
&l开发者_开发问答t;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Untitled Document</title>
<script type="text/javascript">
window.onload = function(){
for(var prop in document.links){
alert(prop); // It does not alert foo!
}
}
</script>
</head>
<body>
<a name="foo" href="#">foo</a>
</body>
</html>
In theory object notation for accessing prop is like: obj.prop.
In object array-like there must be number notation for elements of a object: obj[0], and obj.length.
And alert is giving: 0, length, item, namedItem. First two is from theory of object array-like and other two can be used for accessing props.
And, finally, this link could be found like document.links[0] and document.links.foo. There is no foo prop in document.links. Why? Thanks.
The reason document.links.foo is not available is because you're using name and not id. If you change your markup to:
<a id="foo" href="#">foo</a>
Then this will work:
window.onload = function(){
window.alert(document.links.foo.innerHTML);
}
You're passing the DOM element itself to "alert()". What about passing the "name" attribute?
for(var prop in document.links){
alert(prop.name);
}
Now, it's really a bad idea to iterate through a node list like that:
for (var i = 0; i < document.links.length; ++i)
alert(document.links[i].name);
If you want the text content of the node, then you can try this:
for (var i = 0; i < document.links.length; ++i)
alert(document.links[i].innerHTML);
You could also find its child text nodes and extract their value.
Note that the "links" object will also include <area> tags, if you've got any.
加载中,请稍侯......
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