The first 28 months on the 8th day

Original link: http://www.cnblogs.com/javastart/p/10237766.html

Statistical 1.JS length input string in UTF-8 encoding of

 

/**
 * Calculation bytes of memory occupied by the string, default UTF-8 encoding calculation can be formulated as UTF-16
 * UTF-8 is a variable-length Unicode encoding format, using one to four bytes per character encoding
 * 
 * 000000 - 00007F (128 codes) 0zzzzzzz (00-7F) Byte a
 * 000080 - 0007FF (1920 codes) 110yyyyy (C0-DF) 10zzzzzz (80-BF) two bytes
 * 000800 - 00D7FF 
   00E000 - 00FFFF (61440 codes) 1110xxxx (E0-EF) 10yyyyyy 10zzzzzz three bytes
 * 010000 - 10FFFF (1048576 codes) 11110www (F0-F7) 10xxxxxx 10yyyyyy 10zzzzzz four bytes
 * 
 * Note: Unicode there are no characters in the range D800-DFFF
 * {@link <a onclick="javascript:pageTracker._trackPageview('/outgoing/zh.wikipedia.org/wiki/UTF-8');" href="http://zh.wikipedia.org/wiki/UTF-8">http://zh.wikipedia.org/wiki/UTF-8</a>}
 * 
 * UTF-16 encoding most of two bytes, that out using four bytes 65535
 * 000000 - 00FFFF two bytes
 * 010000 - 10FFFF four bytes
 * 
 * {@link <a onclick="javascript:pageTracker._trackPageview('/outgoing/zh.wikipedia.org/wiki/UTF-16');" href="http://zh.wikipedia.org/wiki/UTF-16">http://zh.wikipedia.org/wiki/UTF-16</a>}
 * @param  {String} str 
 * @param  {String} charset utf-8, utf-16
 * @return {Number}
 */
var sizeof = function (str, charset) {
  var total = 0,
  charCode,
  i,
  only;
  charset = charset ? charset.toLowerCase() : '';
  if (charset === 'utf-16' || charset === 'utf16') {
    for (i = 0, len = str.length; i < len; i++) {
      charCode = str.charCodeAt(i);
      if (charCode <= 0xffff) {
        total += 2;
      } else {
        total += 4;
      }
    }
  } else {
    for (i = 0, len = str.length; i < len; i++) {
      charCode = str.charCodeAt(i);
      if (charCode <= 0x007f) {
        total += 1;
      } else if (charCode <= 0x07ff) {
        total += 2;
      } else if (charCode <= 0xffff) {
        total += 3;
      } else {
        total += 4;
      }
    }
  }
  return total;
};

 

 

https://www.cnblogs.com/dwade/articles/alen.html

Reproduced in: https: //www.cnblogs.com/javastart/p/10237766.html