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quard8/b64.js

Created May 16, 2014 13:02
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Revisions

  1. quard8 created this gist May 16, 2014.
    62 changes: 62 additions & 0 deletions b64.js
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,62 @@
    var Base64 = ( function( ) {

    var _PADCHAR = "=",
    _ALPHA = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";


    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 {
    encode: _encode
    };

    })();