utf-8转换为base64

utf-8转换为base64

var utf8ToBase64={
    encode = function(input, utf8) {
      var output = "";
      var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
      var i = 0;

      while (i < input.length) {

        chr1 = input.charCodeAt(i++);
        chr2 = input.charCodeAt(i++);
        chr3 = input.charCodeAt(i++);

        enc1 = chr1 >> 2;
        enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
        enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
        enc4 = chr3 & 63;

        if (isNaN(chr2)) {
          enc3 = enc4 = 64;
        }
        else if (isNaN(chr3)) {
          enc4 = 64;
        }

        output = output + _keyStr.charAt(enc1) + _keyStr.charAt(enc2) + _keyStr.charAt(enc3) + _keyStr.charAt(enc4);

      }

      return output;
    };
}

base64转换utf-8