javascript - Count characters/sms using jQuery

Question

I count characters using NobleCount and the following code:

$('#message').NobleCount('#messageInfo',{
            max_chars: getMaxChars(),
            on_negative: function(t_obj, char_area, c_settings, char_rem){

            }
});

I want a feature like counting SMS, if the limit is reached the next 160 chars are for the second sms and so on. I can use parameters like on_update, on_positive, on_negative and block_negative.

I tried something using modulo but it does not work. Any ideas?

Answer 1

Beware that SMS is more complicated than you seem to indicate.

Standard "160-character" SMS uses a strange 7-bit encoding that covers most ASCII, some European accents, misc symbols such as €, some capital Greek letters (the ones that don't look like Roman characters).

If your message uses other characters, it can instead be encoded as Unicode using UCS-2 (like UTF-16 but only BMP), for a limit of 70 characters. Actually, the specification says UCS-2, but emoji (non-BMP Unicode) can be sent in SMS so that implies UTF-16 is being used, in which case each emoji must "use up" 2 characters out of the 70 total.

But some languages can use "national language shift tables" which use an alternative 7-bit encoding. Most notably Turkish, but also Spanish, Portuguese, and ten Indian sub-continent languages. These are relatively new additions to the standard.

Even in the 7-bit encoding, a few characters are "escaped" which means they "use up" 2 characters. In the default 7-bit encoding, these are: {}[]|^~€.

If your message goes beyond 160 characters, it can use "concatenated SMS", but then a small header is added to each message, meaning each segment only has room for something like 153 characters. There are two different versions of that header, of different sizes, thus it may not be 153 characters, but 152 (from memory). Similarly for Unicode concatenated SMS, the small header makes it 67 characters per segment.

Good luck with all that!