Length checking in textboxes should be done after the string has been trimmed
Basically lots of textboxes that need a minimum characters (such as reviews and comments) can be made blank by simply adding spaces.
Using trim() before checking the length of the contents of the textboxes will remove whitespaces before and after the string which will allow for more checking.
TL;DR: use the trim() function before checking the length of the contents of textboxes (on comments and reviews for example)