SEO and JavaScript

The use of JavaScript on websites has been widely debated over recent years. Many designers think that JavaScript is essential for modern websites (with the increasing use of AJAX), however many SEO professionals disagree and think that using JavaScript is an unnecessary luxury.

Search engines such as Google and Yahoo are taking usablilty into consideration when ranking sites and therefore the debate described above should influence our SEO work.

JavaScript can be useful when creating interactive websites, however if a user doesn?t have JavaScript enabled then it can end up making a website unusable. It is particularly problamatic if disabling Javascript breaks the websites navigation or expandable content. You?ll notice that if you disable Javascript on the Just Search pages they will still display correctly, and any expandable content or navigation will be expanded by default to display the content. To do this the stylesheet must display the content/navigation by default and the JavaScript should do the retracting of any content.

Google's spiders are unable to read Javascript, however using Javascript to hide page content or to switch content may get penalised by Google. Additionally JavaScript may slow down page loading times which are also becoming a factor for quality scores on PPC. This can be overcome by moving the JavaScript code into an external file.
Therefore from an SEO point of view, the use of Javascript is fine as long as it is implemented correctly and doesn?t affect the usability of the website.

Sam Rutley