javascript - atob 无法在 IE 中工作

Question

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 中工作正常，但在 IE 中不起作用。请告诉我任何替代品，或者如何使其在 IE 中工作

Answer 1

转到此链接并包含其中的 js:

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('');
}