You should first check whether your sketch runs with the index.html file (drag it on the browser) that was exported in the web-export folder.

The index file works fine in a browser, so it's my canvas code maybe? 

I see there are no html tags which are needed before and after everything so that your browser knows that you're writing html.

Yep the tags were in place. In the console, are the errors in red?  Thanks. 

Yea console errors are generally red. The file should be visible where the error was, if it's in processing.js there's something wrong in your sketch. If the error is in index.html you should be able to go to the line number the error is at.