学习使用JavaScript实现UTF-8编解码(2)-木庄网络博客

2022-02-21 13:52:27 PHP中文网 JavaScript 百度已收录

function utf8Decode(inputStr) {
  var outputStr = "";
  var code1, code2, code3, code4;
   
  for(var i = 0; i < inputStr.length; i++) {
    code1 = inputStr.charCodeAt(i);
     
    if(code1 < 128) {
      outputStr += String.fromCharCode(code1);
    }
    else if(code1 < 224) {
      code2 = inputStr.charCodeAt(++i);
      outputStr += String.fromCharCode(((code1 & 31) << 6) | (code2 & 63));
    }
    else if(code1 < 240) {
      code2 = inputStr.charCodeAt(++i);
      code3 = inputStr.charCodeAt(++i);
      outputStr += String.fromCharCode(((code1 & 15) << 12) | ((code2 & 63) << 6) | (code3 & 63));
    }
    else {
      code2 = inputStr.charCodeAt(++i);
      code3 = inputStr.charCodeAt(++i);
      code4 = inputStr.charCodeAt(++i);
      outputStr += String.fromCharCode(((code1 & 7) << 18) | ((code2 & 63) << 12) |((code3 & 63) << 6) | (code2 & 63));
    }
  }
   
  return outputStr;
}