I upgraded to NetBeans 7.3.1 and the new release is flagging some lines as
errors that were not so flagged in release 7.2. The flagged code turns out 
to be a feature that works in JavaScript 1.7. This feature is called "Destructuring Assignment". It is discussed here:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/New_in_JavaScript/1.7?redirectlocale=en-US&redirectslug=JavaScript%2FNew_in_JavaScript%2F1.7#Destructuring_assignment_%28Merge_into_own_page.2Fsection%29

For example in the code:

  var xPix, yPix, index;
  [xPix, yPix] = offsetIn(event, BD18.canvas3); 
  
The second line gets flagged as an error with the message "Invalid left hand side for assignment".

Can I turn off this "Invalid left hand side for assignment" error flag for 
the above code?

I looked in options->hints but I found nothing that looked applicable. 

If there is no feature to control this error message, then one should be 
implemented ASAP because Destructuring Assignment will soon become more
prevalently supported by modern browsers.