base64编码解码(配合encodeURIComponent使

/*
  *  base64编码(编码，配合encodeURIComponent使用)
  *  @parm : str 传入的字符串
  *  使用：
        1、引入util.js(路径更改) :const util  = require('../../utils/util.js');
        2、util.base64_encode(util.utf16to8('base64 编码'));
 */
function base64_encode(str) {
    //下面是64个基本的编码
    var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
    var out, i, len;
    var c1, c2, c3;
    len = str.length;
    i = 0;
    out = "";
    while (i < len) {
      c1 = str.charCodeAt(i++) & 0xff;
      if (i == len) {
        out += base64EncodeChars.charAt(c1 >> 2);
        out += base64EncodeChars.charAt((c1 & 0x3) << 4);
        out += "==";
        break;
      }
      c2 = str.charCodeAt(i++);
      if (i == len) {
        out += base64EncodeChars.charAt(c1 >> 2);
        out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
        out += base64EncodeChars.charAt((c2 & 0xF) << 2);
        out += "=";
        break;
      }
      c3 = str.charCodeAt(i++);
      out += base64EncodeChars.charAt(c1 >> 2);
      out += base64EncodeChars.charAt(((c1 & 0x3) << 4) | ((c2 & 0xF0) >> 4));
      out += base64EncodeChars.charAt(((c2 & 0xF) << 2) | ((c3 & 0xC0) >> 6));
      out += base64EncodeChars.charAt(c3 & 0x3F);
    }
    return out;
  }
  /*
    *  base64编码(编码，配合encodeURIComponent使用)
    *  @parm : str 传入的字符串
   */
  function utf16to8(str) {
    var out, i, len, c;
    out = "";
    len = str.length;
    for (i = 0; i < len; i++) {
      c = str.charCodeAt(i);
      if ((c >= 0x0001) && (c <= 0x007F)) {
        out += str.charAt(i);
      } else if (c > 0x07FF) {
        out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
        out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));
        out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
      } else {
        out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F));
        out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
      }
    }
    return out;
  }
  
  /*
    *  base64解码(配合decodeURIComponent使用)
    *  @parm : input 传入的字符串
    *  使用：
          1、引入util.js(路径更改) :const util  = require('../../utils/util.js');
          2、util.base64_decode('YmFzZTY0IOe8lueggQ==');
   */
  function base64_decode(input) {
    var base64EncodeChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
    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 = base64EncodeChars.indexOf(input.charAt(i++));
      enc2 = base64EncodeChars.indexOf(input.charAt(i++));
      enc3 = base64EncodeChars.indexOf(input.charAt(i++));
      enc4 = base64EncodeChars.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);
      }
    }
    return utf8_decode(output);
  }
  
  /*
    *  utf-8解码
    *  @parm : utftext 传入的字符串
   */
  function utf8_decode(utftext) {
    var string = '';
    let i = 0;
    let c = 0;
    let c1 = 0;
    let c2 = 0;
    while (i < utftext.length) {
      c = utftext.charCodeAt(i);
      if (c < 128) {
        string += String.fromCharCode(c);
        i++;
      } else if ((c > 191) && (c < 224)) {
        c1 = utftext.charCodeAt(i + 1);
        string += String.fromCharCode(((c & 31) << 6) | (c1 & 63));
        i += 2;
      } else {
        c1 = utftext.charCodeAt(i + 1);
        c2 = utftext.charCodeAt(i + 2);
        string += String.fromCharCode(((c & 15) << 12) | ((c1 & 63) << 6) | (c2 & 63));
        i += 3;
      }
    }
    return string;
  }
  
  /*
      * base64编码函数封装
      * @parm: str(传入要编成base64的内容)
      * 使用：
          1、引入util.js(路径更改) :const util  = require('../../utils/util.js');
          2、util.baseEncode('base64 编码');
  */
  function baseEncode(str) {
    return base64_encode(utf16to8(str));
  }
  /*
      * base64解码函数封装
      * @parm: str(传入要解为正常字体)
      * 使用：
          1、引入util.js(路径更改) :const util  = require('../../utils/util.js');
          2、util.baseDecode(util.baseEncode('base64 编码'))
  */
  function baseDecode(str) {
    return base64_decode(str);
  }// 抛出函数使用
  module.exports = {
    baseEncode: baseEncode,
    baseDecode: baseDecode
  }