Created
November 11, 2011 15:56
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Function to count bytes of a string (UTF8)
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| /** | |
| * Function to fix native charCodeAt() | |
| * | |
| * Now, we can use fixedCharCodeAt("foo€", 3); for multibyte (non-bmp) chars too. | |
| * | |
| * @access public | |
| * @see https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/String/charCodeAt | |
| * @note If you hit a non-bmp surrogate, the function will return false | |
| * @param str String Mixed string to get charcodes | |
| * @param idx Integer Position of the char to get | |
| * @return code Integer Result charCodeAt(); | |
| */ | |
| function fixedCharCodeAt(str, idx) { | |
| idx = idx || 0; | |
| var code = str.charCodeAt(idx); | |
| var hi, low; | |
| if (0xD800 <= code && code <= 0xDBFF) { // High surrogate (could change last hex to 0xDB7F to treat high private surrogates as single characters) | |
| hi = code; | |
| low = str.charCodeAt(idx + 1); | |
| if (isNaN(low)) { | |
| throw 'Kein gültiges Schriftzeichen oder Speicherfehler!'; | |
| } | |
| return ((hi - 0xD800) * 0x400) + (low - 0xDC00) + 0x10000; | |
| } | |
| if (0xDC00 <= code && code <= 0xDFFF) { // Low surrogate | |
| // We return false to allow loops to skip this iteration since should have already handled high surrogate above in the previous iteration | |
| return false; | |
| /*hi = str.charCodeAt(idx-1); | |
| low = code; | |
| return ((hi - 0xD800) * 0x400) + (low - 0xDC00) + 0x10000;*/ | |
| } | |
| return code; | |
| } | |
| /** | |
| * Gets size of a UTF-8 string in bytes | |
| * | |
| * @autor Frank Neff <[email protected]> | |
| * @license GPL v2 | |
| * @access public | |
| * @param str String Input string to get bytesize | |
| * @return result String Size of the input string in bytes | |
| */ | |
| function countUtf8(str) { | |
| var result = 0; | |
| for (var n = 0; n < str.length; n++) { | |
| var charCode = fixedCharCodeAt(str, n); | |
| if (typeof charCode === "number") { | |
| if (charCode < 128) { | |
| result = result + 1; | |
| } else if (charCode < 2048) { | |
| result = result + 2; | |
| } else if (charCode < 65536) { | |
| result = result + 3; | |
| } else if (charCode < 2097152) { | |
| result = result + 4; | |
| } else if (charCode < 67108864) { | |
| result = result + 5; | |
| } else { | |
| result = result + 6; | |
| } | |
| } | |
| } | |
| return result; | |
| } |
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| <html> | |
| <head> | |
| <title>String size with countUtf8</title> | |
| <script type="text/javascript" src="count_utf8.js"></script> | |
| </head> | |
| <body> | |
| <script type="text/javascript"> | |
| document.write( "The string size in bytes is " + countUtf8("a€bð¤Â¢") ); | |
| </script> | |
| </body> | |
| </html> |
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Code is now fixed up, and works with non-bmp characters too ;)