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