Tutorial :How to let Eclipse accept the canvas tag?


I installed the Aptana plugin in my Eclipse, and I use canvas tag in my html file. I find that the Eclipse can't recognize the canvas tag, it highlight my canvas tags, and display follow msg:

< canvas > is not recognized

How can I fix this problem? thx in advance.


This is most likely coming from the Tidy HTML validator packaged with Aptana's version of Eclipse. If you open the preferences for your HTML browser within Aptana, you can add a regular expression to filter the validation errors.

This can be done by going to the Window > Preferences dialog window. Then, expand Aptana > HTML and select 'Validation'.

The filter would probably look like this:

.*<canvas> is not recognized.*


The specific rule under the Aptana>Editors>HTML>Validation filter is

.*<\s*canvas\s*> is not recognized.*

Doing something more generic like .* is not recognized.* lets any Bad Tag in


The answer, in clear terms, is to go to the HTML>Validation view under preferences as Malaxeur said (for Aptana2 on OSX it was Aptana Studio>Preferences, then Aptana>Editors>HTML>Validation), and create a new rule that resembles the following.

.* is not recognized.*  

that's what worked for me. how or why it works, i can't explain.


The error will disappear if using the HTML5 doctype and a more recent version of Eclipse. I'm running Eclipse IDE for Java EE Developers (Build id: 20110218-0911) and do not have this issue.


I think it's already fixed in the current Aptana 3 beta. But in Aptana 2 it's still a problem. To allow not all, but multiple HTML5 Tags you could do it with a filter rule like that:

<(nav|header|section|article|canvas)> is not recognized.  

Of course there are some more tags to consider. Just add the ones you need.

Note:If u also have question or solution just comment us below or mail us on toontricks1994@gmail.com
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