Javascript atob 不能在 IE 中工作

atob not working in IE

提问by Paritosh Singh

I am trying to use atob for converting base64 encoded data to string. I found its working fine in Mozilla and Chrome, but it is not working in IE. Please tell me any substitue for this, or how to make this work in IE

我正在尝试使用 atob 将 base64 编码数据转换为字符串。我发现它在 Mozilla 和 Chrome 中运行良好，但在 IE 中不起作用。请告诉我任何替代品，或者如何在 IE 中进行这项工作

回答by Paritosh Singh

Go to this link and include js present there:

转到此链接并在那里包含 js：

http://code.google.com/p/stringencoders/source/browse/trunk/javascript/base64.js?r=230

http://code.google.com/p/stringencoders/source/browse/trunk/javascript/base64.js?r=230

/*
 * Copyright (c) 2010 Nick Galbreath
 * See full license on http://code.google.com/p/stringencoders/source/browse/#svn/trunk/javascript
 */

var base64 = {};
base64.PADCHAR = '=';
base64.ALPHA = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';

base64.makeDOMException = function() {
    // sadly in FF,Safari,Chrome you can't make a DOMException
    var e, tmp;

    try {
        return new DOMException(DOMException.INVALID_CHARACTER_ERR);
    } catch (tmp) {
        // not available, just passback a duck-typed equiv
        // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Error
        // https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Error/prototype
        var ex = new Error("DOM Exception 5");

        // ex.number and ex.description is IE-specific.
        ex.code = ex.number = 5;
        ex.name = ex.description = "INVALID_CHARACTER_ERR";

        // Safari/Chrome output format
        ex.toString = function() { return 'Error: ' + ex.name + ': ' + ex.message; };
        return ex;
    }
}

base64.getbyte64 = function(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 = base64.ALPHA.indexOf(s.charAt(i));
    if (idx === -1) {
        throw base64.makeDOMException();
    }
    return idx;
}

base64.decode = function(s) {
    // convert to string
    s = '' + s;
    var getbyte64 = base64.getbyte64;
    var pads, i, b10;
    var imax = s.length
    if (imax === 0) {
        return s;
    }

    if (imax % 4 !== 0) {
        throw base64.makeDOMException();
    }

    pads = 0
    if (s.charAt(imax - 1) === base64.PADCHAR) {
        pads = 1;
        if (s.charAt(imax - 2) === base64.PADCHAR) {
            pads = 2;
        }
        // either way, we want to ignore this last block
        imax -= 4;
    }

    var x = [];
    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('');
}

base64.getbyte = function(s,i) {
    var x = s.charCodeAt(i);
    if (x > 255) {
        throw base64.makeDOMException();
    }
    return x;
}

base64.encode = function(s) {
    if (arguments.length !== 1) {
        throw new SyntaxError("Not enough arguments");
    }
    var padchar = base64.PADCHAR;
    var alpha   = base64.ALPHA;
    var getbyte = base64.getbyte;

    var i, b10;
    var x = [];

    // convert to string
    s = '' + s;

    var 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('');
}

回答by Satya Teja

atob and btoa are mozilla specific functions afterwards the support was extended to webkit browser like chrome,safari so it doesn't work in IE.

atob 和 btoa 是 mozilla 特定的功能，后来支持扩展到 webkit 浏览器，如 chrome、safari，因此它在 IE 中不起作用。

So better use some other functions like :-

所以最好使用其他一些功能，例如：-

/**
*
*  Base64 encode / decode
*  http://www.webtoolkit.info/
*
**/

var Base64 = {

    // private property
    _keyStr : "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",

    // public method for encoding
    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;
    },

    // public method for decoding
    decode : function (input) {
        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 = this._keyStr.indexOf(input.charAt(i++));
            enc2 = this._keyStr.indexOf(input.charAt(i++));
            enc3 = this._keyStr.indexOf(input.charAt(i++));
            enc4 = this._keyStr.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);
            }

        }

        output = Base64._utf8_decode(output);

        return output;

    },

    // private method for UTF-8 encoding
    _utf8_encode : function (string) {
        string = string.replace(/\r\n/g,"\n");
        var utftext = "";

        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;
    },

    // private method for UTF-8 decoding
    _utf8_decode : function (utftext) {
        var string = "";
        var i = 0;
        var c = c1 = c2 = 0;

        while ( i < utftext.length ) {

            c = utftext.charCodeAt(i);

            if (c < 128) {
                string += String.fromCharCode(c);
                i++;
            }
            else if((c > 191) && (c < 224)) {
                c2 = utftext.charCodeAt(i+1);
                string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
                i += 2;
            }
            else {
                c2 = utftext.charCodeAt(i+1);
                c3 = utftext.charCodeAt(i+2);
                string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
                i += 3;
            }

        }

        return string;
    }

}

this will resolve your problem

这将解决您的问题