get_link_for_letter.js

/* get_link_for_letter(2019xxxx, YYMMDD, "이름석자"); */
function get_link_for_letter(date_to_enter, date_of_birth, name) {
  date_to_enter = Base64.encode(date_to_enter + "");
  date_of_birth = Base64.encode(date_of_birth + "");
  return `http://www.katc.mil.kr/katc/community/children.jsp?search:search_key1:child_search=etc_char8&search:search_key2:child_search=etc_char9&search:search_key3:child_search=etc_char1&search_val1=${date_to_enter}&search_val2=${date_of_birth}&search_val3=${name}`
}

// Base64 from cms.js from http://www.katc.mil.kr
var Base64 = {
  _keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
  encode: function(input) {
    var output = "";
    var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
    var i = 0;
    input = Base64._utf8_encode(input);
    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 + this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) + this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4)
    }
    return output
  },
  decode: function(input) {
    var output = "";
    var chr1, chr2, chr3;
    var enc1, enc2, enc3, enc4;
    var i = 0;
    input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
    while (i < input.length) {
      enc1 = this._keyStr.indexOf(input.charAt(i++));
      enc2 = this._keyStr.indexOf(input.charAt(i++));
      enc3 = this._keyStr.indexOf(input.charAt(i++));
      enc4 = this._keyStr.indexOf(input.charAt(i++));
      chr1 = (enc1 << 2) | (enc2 >> 4);
      chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
      chr3 = ((enc3 & 3) << 6) | enc4;
      output = output + String.fromCharCode(chr1);
      if (enc3 != 64) {
        output = output + String.fromCharCode(chr2)
      }
      if (enc4 != 64) {
        output = output + String.fromCharCode(chr3)
      }
    }
    output = Base64._utf8_decode(output);
    return output
  },
  _utf8_encode: function(string) {
    string = string.replace(/\r\n/g, "\n");
    var utftext = "";
    for (var n = 0; n < string.length; n++) {
      var c = string.charCodeAt(n);
      if (c < 128) {
        utftext += String.fromCharCode(c)
      } else if ((c > 127) && (c < 2048)) {
        utftext += String.fromCharCode((c >> 6) | 192);
        utftext += String.fromCharCode((c & 63) | 128)
      } else {
        utftext += String.fromCharCode((c >> 12) | 224);
        utftext += String.fromCharCode(((c >> 6) & 63) | 128);
        utftext += String.fromCharCode((c & 63) | 128)
      }
    }
    return utftext
  },
  _utf8_decode: function(utftext) {
    var string = "";
    var i = 0;
    var c = c1 = c2 = 0;
    while (i < utftext.length) {
      c = utftext.charCodeAt(i);
      if (c < 128) {
        string += String.fromCharCode(c);
        i++
      } else if ((c > 191) && (c < 224)) {
        c2 = utftext.charCodeAt(i + 1);
        string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
        i += 2
      } else {
        c2 = utftext.charCodeAt(i + 1);
        c3 = utftext.charCodeAt(i + 2);
        string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
        i += 3
      }
    }
    return string
  }
}