First of all, I noticed that some of the textarea counter scripts date back to at least 2000, so this has been a problem that developers have been looking to solve for 8 years. I checked the HTML 5 specification and found that in HTML 5, the textarea element has a maxlength attribute. Presumably user agents will build in the most elegant solution.

But what is the current most elegant solution?
I checked a couple sites that I know use textarea counters well: Delicious and Twitter.

Delicious

Textarea counters on Delicious.com

Twitter

Textarea counters on Twitter.com

I like how prominent the character count is in Twitter, although perhaps too terse, but if Javascript is disabled it displays nothing at all. On the other hand, in Delicious displays “1000 characters max” if Javascript is off (instead of “1000 characters left”), which is still useful information. (I would avoid using the abbreviation max, though, and use maximum or limit instead, which might be better understood by those for whom English is a second language.)

I like Twitter’s “warning track” that lets the user know they need to keep it concise and wrap it up, although I find it confusing that they used bright red to denote both the “dangerously close to” as well as “over” the limit. The positive bright red numbers could easily be misconstrued as over the limit, since red is a color we frequently use to denote errors.

Twitter’s counter responds to onBlur and onChange, whereas the counter in Delicious is triggered by neither.

Both get one thing right that I think most other textarea counters get wrong: they don’t truncate the user’s text. Deleting something that the user has typed (or pasted) is definitely a bad idea for at least two reasons: the user may not realize the input was truncated and may submit incomplete info, and that the user, upon discovering that the input requires editing, may choose to cut text from someplace other than the end. Instead, both versions alert the user that they are over the limit and provide information on how many characters need to be cut to stay within the limit.

(As an aside, one thing I find curious is that both count an Enter keystroke as one character. I’ve run into issues with this before because a line break on a Windows-based system should insert 2 ASCII characters: a Carriage Return (CR) and a Line Feed (LF). *nix systems, including OS X, will insert a Line Feed (LF). However, I haven’t been able to reproduce this issue with recent testing. If it is still an issue, I imagine they handle this on the back-end by converting the CRLF to LF before inserting it into the database?)

In short, my recommendations are:

• Don’t truncate the user’s input; let the user correct it
• Let the user know how far over the limit he or she is
• Provide guidelines even if Javascript is disabled
• onBlur and onChange should also trigger the counter, in case the user is pasting text
• Keep the counter message simple and clear

Another idea I had for a visual counter:

Counter - characters remaining

How can a counter be implemented programatically?
I would like to set something up so that the appropriate event handlers are attached to textarea elements automatically. I found a jQuery plugin, Char Limit, but in addition to not meeting the recommendations I made above, I don’t like how the developer has to specify the character limit in the Javascript (and apply the same limit for all textarea elements).

I think a clever, although imperfect, solution would be to have jQuery (or any Javascript of your choice) turn any static character limit messages (like the one that Delicious provides if Javascript is disabled) into dynamic character counters. For example, with the following code, the Javascript could find any elements with id attributes matching *_counter, take the numeric part as the limit, and build a character counter:
<textarea name="example" id="example"></textarea>
<div id="example_counter">300 characters maximum</div>

It’s problematic for several reasons: another element on the page could have an id that matches *_counter, the non-Javascript message could contain more than one numeric part, and the developers would have be consistent in naming the textareas and accompanying divs. But I think it is in many ways an improvement over the inline Javascript I’ve seen in some oft-used solutions.

Paste!

Almost all of them rely on the onKeyDown and onKeyUp events to trigger the script. However, some users still manage to submit text that exceeded the limits, even though the application required Javascript. I could not for the life of me reproduce this issue…until today.

Naturally, when I tried to enter text into the textarea, I just typed it there. But that’s not always what users do. Can you imagine, some users might actually compose text in, say, Microsoft Word and then paste it into a textarea? Maybe they are taking advantage of the spell-checker or grammar-checker. Maybe it’s text that they have composed once, but are submitting to several different sites. Or maybe it’s some reason I can’t even fathom!

When I copy-and-paste text, I highlight it, hit CTRL-c, put my cursor at the destination, and hit CTRL-v. But that’s not always what users do either. And as it turns out, if you right-click and select Paste, neither onKeyDown or onKeyUp are triggered. Adding onBlur and onChange seem to do the trick, though.

Of course, this discovery hasn’t exactly solved the problem: the script we are using simply truncates text that is too long. In Firefox, if your textarea has a scrollbar, it could show the user just the top portion of his or her pasted text. Everything would look OK, and the character count displayed would show, for example, 500 of 500 characters.

I haven’t written a replacement script yet, but something clearly needs to alert the user that text has been truncated. At least, however, I have identified the problem.