javascript base64代码

 /**
        *
        *  Base64 encode / decode
        *  http://www.webtoolkit.info
        *
        **/
        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;
            },
            _utf8_encode: function (string) {
                var utftext = "";
                string = string.replace(/\r\n/g, "\n");
                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;
            }
        }

内容不大，无需放到js里影响网站打开速度。