7 * Enforces a byte limit to a textbox, so that UTF-8 entries are not arbitrarily truncated.
9 $.fn
.byteLimit = function( limit
) {
10 return $(this).attr( 'maxLength', limit
).keypress( function( e
) {
11 // first check to see if this is actually a character key
13 // Based on key-event info from http://unixpapa.com/js/key.html
14 // jQuery should also normalize e.which to be consistent cross-browser,
15 // however the same check is still needed regardless of jQuery.
17 // Note: At the moment, for some older opera versions (~< 10.5)
18 // some special keys won't be recognized (aka left arrow key).
19 // Backspace will be, so not big issue.
21 if ( e
.which
=== 0 || e
.charCode
=== 0 || e
.which
=== 8 ||
22 e
.ctrlKey
|| e
.altKey
|| e
.metaKey
)
24 return true; //a special key (backspace, etc) so don't interfere.
27 // This basically figures out how many bytes a UTF-16 string (which is what js sees)
28 // will take in UTF-8 by replacing a 2 byte character with 2 *'s, etc, and counting that.
29 // Note, surrogate (\uD800-\uDFFF) characters are counted as 2 bytes, since there's two of them
30 // and the actual character takes 4 bytes in UTF-8 (2*2=4). Might not work perfectly in edge cases
31 // such as illegal sequences, but that should never happen.
33 var len
= this.value
.replace( /[\u0080-\u07FF\uD800-\uDFFF]/g, '**' ).replace( /[\u0800-\uD7FF\uE000-\uFFFF]/g, '***' ).length
;
34 // limit-3 as this doesn't count character about to be inserted.
35 if ( len
> ( limit
-3 ) ) {