joern.zaefferer

Ever got annoyed when submitting a comment on a wordpress blog and just getting a blank page with a error message like “please fill out required fields” and nothing else? This plugin aims to help by adding validation to the comment form. When a user submits the form and something is missing, an appropiate message is displayed and individual fields are highlighted. When the email or url is in an incorrect format, a message is displayed accordingly.
Why should you install it? Because you care for comments and want to help users reduce mistakes that hold them off from commenting at all.
Whats the technology used? <a href="http://jquery.com" rel="nofollow ugc">jQuery</a> and the <a href="http://bassistance.de/jquery-plugins/jquery-plugin-validation/" rel="nofollow ugc">jQuery Validation plugin</a> with a few customizations to make it fit into the standard WordPress theme.
Is it compatible with other plugins? The plugin is tested with the <a href="https://wordpress.org/extend/plugins/draw-comments/" rel="ugc">Draw Comments</a> plugin and works, though the performance is slightly degraded. Other plugins haven’t yet been tested.

Comment Validation

This plugin adds client-side validation to the Wordpress comment form, using the jQuery validation plugin.

shawfactor

This plugin can greatly improve the user experience for your blog, by automatically and periodically saving fields like “just typed” comment (the content textarea input box in comment section), the visitors email, and vitors name (in the comment form).
The comment is saved using client side indexeddd (falling back to localstorage), this prevents loss of unsubmitted content.
This is similar like WordPress can remember your Name, Email, Website in comment area for the next visit, but WP Local Storage plugin extends this into next level, it can remember the actual unsaved comment (i.e. before hit submit button) so even the browser is crashed before the user hit save, it is okay! When the user came back, all “just type comment” will be still in there.
More importantly all data is saved client side, nothing is sent to the server. Thus maintaining visitor privacy!

LH Localforage

This plugin automatically and periodically saves the "just typed comment" so no data will be lost even if the browser crashes.

Comment Validation vs LH Localforage