Base64编解码 ---- 支持64编码

Posted 2020-12-16 serahuli

1. 原生js的Base64方法

encodeURIComponent() 函数可把字符串作为 URI 组件进行编码,有一个必传参数.

unescape() 函数可对通过 escape() 编码的字符串进行解码。

// base编码
// value 是编码后的值
// input 是需要编码的值
function base64Encode(input){
  let value;
  value = encodeURIComponent(input);
  value = unescape(value);
  value = window.btoa(value);
  return value;
}

// base解码
// value 是解码后的值
// input 是需要解码的值
function base64Decode(input){
  let value
  value = window.atob(input);
  value = escape(value);
  value = decodeURIComponent(value);
  return value;
}

JQuery 的 base64编码

1、 下载 jquery.base64.js

jQuery.base64 = ( function( $ ) {

  var _PADCHAR = "=",
    _ALPHA = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",
    _VERSION = "1.1";//Mr. Ruan fix to 1.1 to support asian char(utf8)


  function _getbyte64( s, i ) {
    // This is oddly fast, except on Chrome/V8.
    // Minimal or no improvement in performance by using a
    // object with properties mapping chars to value (eg. ‘A‘: 0)

    var idx = _ALPHA.indexOf( s.charAt( i ) );

    if ( idx === -1 ) {
      throw "Cannot decode base64";
    }

    return idx;
  }

  function _decode_chars(y, x){
    while(y.length > 0){
      var ch = y[0];
      if(ch < 0x80) {
        y.shift();
        x.push(String.fromCharCode(ch));
      }else if((ch & 0x80) == 0xc0){
        if(y.length < 2) break;
        ch = y.shift();
        var ch1 = y.shift();
        x.push(String.fromCharCode( ((ch & 0x1f) << 6) + (ch1 & 0x3f)));
      }else{
        if(y.length < 3) break;
        ch = y.shift();
        var ch1 = y.shift();
        var ch2 = y.shift();
        x.push(String.fromCharCode(((ch & 0x0f) << 12) + ((ch1 & 0x3f) << 6) + (ch2 & 0x3f)));
      }
    }
  }

  function _decode( s ) {
    var pads = 0,
      i,
      b10,
      imax = s.length,
      x = [],
      y = [];

    s = String( s );

    if ( imax === 0 ) {
      return s;
    }

    if ( imax % 4 !== 0 ) {
      throw "Cannot decode base64";
    }

    if ( s.charAt( imax - 1 ) === _PADCHAR ) {
      pads = 1;

      if ( s.charAt( imax - 2 ) === _PADCHAR ) {
        pads = 2;
      }

      // either way, we want to ignore this last block
      imax -= 4;
    }

    for ( i = 0; i < imax; i += 4 ) {
      var ch1 = _getbyte64( s, i );
      var ch2 = _getbyte64( s, i + 1);
      var ch3 = _getbyte64( s, i + 2);
      var ch4 = _getbyte64( s, i + 3);

      b10 = ( _getbyte64( s, i ) << 18 ) | ( _getbyte64( s, i + 1 ) << 12 ) | ( _getbyte64( s, i + 2 ) << 6 ) | _getbyte64( s, i + 3 );
      y.push(b10 >> 16);
      y.push((b10 >> 8) & 0xff);
      y.push(b10 & 0xff);
      _decode_chars(y, x);
    }
    switch ( pads ) {
      case 1:
        b10 = ( _getbyte64( s, i ) << 18 ) | ( _getbyte64( s, i + 1 ) << 12 ) | ( _getbyte64( s, i + 2 ) << 6 );
        y.push(b10 >> 16);
        y.push((b10 >> 8) & 0xff);
        break;

      case 2:
        b10 = ( _getbyte64( s, i ) << 18) | ( _getbyte64( s, i + 1 ) << 12 );
        y.push(b10 >> 16);
        break;
    }
    _decode_chars(y, x);
    if(y.length > 0) throw "Cannot decode base64";
    return x.join( "" );
  }


  function _get_chars(ch, y){
    if(ch < 0x80) y.push(ch);
    else if(ch < 0x800){
      y.push(0xc0 + ((ch >> 6) & 0x1f));
      y.push(0x80 + (ch & 0x3f));
    }else{
      y.push(0xe0 + ((ch >> 12) & 0xf));
      y.push(0x80 + ((ch >> 6) & 0x3f));
      y.push(0x80 + (ch & 0x3f));
    }
  }



  function _encode( s ) {
    if ( arguments.length !== 1 ) {
      throw "SyntaxError: exactly one argument required";
    }

    s = String( s );
    if ( s.length === 0 ) {
      return s;
    }

    //s = _encode_utf8(s);
    var i,
      b10,
      y = [],
      x = [],
      len = s.length;
    i = 0;
    while(i < len){
      _get_chars(s.charCodeAt(i), y);
      while(y.length >= 3){
        var ch1 = y.shift();
        var ch2 = y.shift();
        var ch3 = y.shift();
        b10 = ( ch1 << 16 ) | ( ch2 << 8 ) | ch3;
        x.push( _ALPHA.charAt( b10 >> 18 ) );
        x.push( _ALPHA.charAt( ( b10 >> 12 ) & 0x3F ) );
        x.push( _ALPHA.charAt( ( b10 >> 6 ) & 0x3f ) );
        x.push( _ALPHA.charAt( b10 & 0x3f ) );
      }
      i++;
    }


    switch ( y.length ) {
      case 1:
        var ch = y.shift();
        b10 = ch << 16;
        x.push( _ALPHA.charAt( b10 >> 18 ) + _ALPHA.charAt( ( b10 >> 12 ) & 0x3F ) + _PADCHAR + _PADCHAR );
        break;

      case 2:
        var ch1 = y.shift();
        var ch2 = y.shift();
        b10 = ( ch1 << 16 ) | ( ch2 << 8 );
        x.push( _ALPHA.charAt( b10 >> 18 ) + _ALPHA.charAt( ( b10 >> 12 ) & 0x3F ) + _ALPHA.charAt( ( b10 >> 6 ) & 0x3f ) + _PADCHAR );
        break;
    }

    return x.join( "" );
  }


  return {
    decode: _decode,
    encode: _encode,
    VERSION: _VERSION
  };

}( jQuery ) );

2、 使用编码解码

// 解码
$.base64.decode(‘要解码的字符串‘)

// 编码
$.base64.encode(‘要编码的字符串‘)