Using Javascript
Although there is no definitive proof that extensive amounts
of java script negatively effect search engine placement,
observation of spider's habits does show that excessive java
script can occasionally trip up a spider. Thus, whenever possible,
JavaScript should be placed in an external .js file and simply
called from the HTML code.
Creating an external java script file is quite simple and
allows you to reference the same script from several pages
without having to duplicate the code. Simply save your java
script as a text file with a .js extension on it. To refer
to this script from your HTML code, simply call the file similar
to how you would call an include or image file.
< script src="filename.js" type="javascript"
>< /script >
This code will tell the browser to apply the java script
it finds in that location to that spot of your web page. The
java script will function normally when someone views the
page with a browser, but will not be read by a search engine
spider as it indexes your web site.
Because search engines are unable to read java script, navigation
systems built entirely with java script (such as drop-down
menus) are neither read, nor indexed by spiders. Just as sites
featuring Flash navigation must provide spiders with an alternative
route to follow links, sites using java script navigation
should include a duplicate, textual navigation system at the
bottom of the page.
For pages built solely with Flash navigation, it's extremely
important to remember that search engines will be unable to
read, and therefore unable to follow any of the Flash navigational
links. This means that unless you provide alternate navigation,
the search engine's spider is unlikely to get past the index
page. This can prevent your web site from having a shot at
ranking highly for internal, content-rich pages. For this
reason, any site that employs Flash navigation should include
a duplicate, spider-friendly navigational system.
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