jquery.base64.js

/*jslint adsafe: false, bitwise: true, browser: true, cap: false, css: false,
  debug: false, devel: true, eqeqeq: true, es5: false, evil: false,
  forin: false, fragment: false, immed: true, laxbreak: false, newcap: true,
  nomen: false, on: false, onevar: true, passfail: false, plusplus: true,
  regexp: false, rhino: true, safe: false, strict: false, sub: false,
  undef: true, white: false, widget: false, windows: false */
/*global jQuery: false, window: false */
"use strict";

/*
 * Original code (c) 2010 Nick Galbreath
 * http://code.google.com/p/stringencoders/source/browse/#svn/trunk/javascript
 *
 * jQuery port (c) 2010 Carlo Zottmann
 * http://github.com/carlo/jquery-base64
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use,
 * copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
 * conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
*/

/* base64 encode/decode compatible with window.btoa/atob
 *
 * window.atob/btoa is a Firefox extension to convert binary data (the "b")
 * to base64 (ascii, the "a").
 *
 * It is also found in Safari and Chrome.  It is not available in IE.
 *
 * if (!window.btoa) window.btoa = $.base64.encode
 * if (!window.atob) window.atob = $.base64.decode
 *
 * The original spec's for atob/btoa are a bit lacking
 * https://developer.mozilla.org/en/DOM/window.atob
 * https://developer.mozilla.org/en/DOM/window.btoa
 *
 * window.btoa and $.base64.encode takes a string where charCodeAt is [0,255]
 * If any character is not [0,255], then an exception is thrown.
 *
 * window.atob and $.base64.decode take a base64-encoded string
 * If the input length is not a multiple of 4, or contains invalid characters
 *   then an exception is thrown.
 */
 
jQuery.base64 = ( function( $ ) {
  
  var _PADCHAR = "=",
    _ALPHA = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/",
    _VERSION = "1.0";


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

    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 ) {
      b10 = ( _getbyte64( s, i ) << 18 ) | ( _getbyte64( s, i + 1 ) << 12 ) | ( _getbyte64( s, i + 2 ) << 6 ) | _getbyte64( s, i + 3 );
      x.push( String.fromCharCode( b10 >> 16, ( b10 >> 8 ) & 0xff, b10 & 0xff ) );
    }

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

      case 2:
        b10 = ( _getbyte64( s, i ) << 18) | ( _getbyte64( s, i + 1 ) << 12 );
        x.push( String.fromCharCode( b10 >> 16 ) );
        break;
    }

    return x.join( "" );
  }
  
  
  function _getbyte( s, i ) {
    var x = s.charCodeAt( i );

    if ( x > 255 ) {
      throw "INVALID_CHARACTER_ERR: DOM Exception 5";
    }
    
    return x;
  }


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

    s = String( s );

    var i,
      b10,
      x = [],
      imax = s.length - s.length % 3;

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

    for ( i = 0; i < imax; i += 3 ) {
      b10 = ( _getbyte( s, i ) << 16 ) | ( _getbyte( s, i + 1 ) << 8 ) | _getbyte( s, i + 2 );
      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 ) );
    }

    switch ( s.length - imax ) {
      case 1:
        b10 = _getbyte( s, i ) << 16;
        x.push( _ALPHA.charAt( b10 >> 18 ) + _ALPHA.charAt( ( b10 >> 12 ) & 0x3F ) + _PADCHAR + _PADCHAR );
        break;

      case 2:
        b10 = ( _getbyte( s, i ) << 16 ) | ( _getbyte( s, i + 1 ) << 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 ) );