如何在JavaScript中将字符串编码为Base64？

Question

如何在JavaScript中将字符串编码为Base64？

javascriptbase64binaryfiles

1218

我有一个可以将PNG图像编码为Base64字符串的PHP脚本。

我想使用JavaScript完成同样的事情。我知道如何打开文件，但是不确定如何进行编码。我不习惯处理二进制数据。

- username

2

以下是使用JavaScript进行base64编码和解码的最佳方法。请参见下面的链接。 http://phpjs.org/functions/base64_encode:358 http://phpjs.org/functions/base64_decode:357 - gautamlakum

这是另一个 jQuery 插件用于 Base64 编码/解码：http://archive.plugins.jquery.com/project/base64 - zahid9i

请检查Microjs: http://microjs.com/#base64 - Vinod Srivastav

参考元问题 *基本相同的答案-唯一的区别：错误的更正*。 - Peter Mortensen

33个回答

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Joe Dyndale · Answer 1

基本上，我只是稍微整理了原始代码，以便JSLint不会抱怨太多，同时我将在注释中标记为私有的方法实际上设置为私有。我还添加了两种在自己的项目中需要的方法，即decodeToHex和encodeFromHex。

代码如下：

var Base64 = (function() {
    "use strict";

    var _keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

    var _utf8_encode = function (string) {

        var utftext = "", c, n;

        string = string.replace(/\r\n/g,"\n");

        for (n = 0; n < string.length; n++) {

            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;
    };

    var _utf8_decode = function (utftext) {
        var string = "", i = 0, c = 0, c1 = 0, c2 = 0;

        while ( i < utftext.length ) {

            c = utftext.charCodeAt(i);

            if (c < 128) {

                string += String.fromCharCode(c);
                i++;

            } else if((c > 191) && (c < 224)) {

                c1 = utftext.charCodeAt(i+1);
                string += String.fromCharCode(((c & 31) << 6) | (c1 & 63));
                i += 2;

            } else {

                c1 = utftext.charCodeAt(i+1);
                c2 = utftext.charCodeAt(i+2);
                string += String.fromCharCode(((c & 15) << 12) | ((c1 & 63) << 6) | (c2 & 63));
                i += 3;
            }
        }
        return string;
    };

    var _hexEncode = function(input) {
        var output = '', i;

        for(i = 0; i < input.length; i++) {
            output += input.charCodeAt(i).toString(16);
        }

        return output;
    };

    var _hexDecode = function(input) {
        var output = '', i;

        if(input.length % 2 > 0) {
            input = '0' + input;
        }

        for(i = 0; i < input.length; i = i + 2) {
            output += String.fromCharCode(parseInt(input.charAt(i) + input.charAt(i + 1), 16));
        }
        return output;
    };

    var encode = function (input) {
        var output = "", chr1, chr2, chr3, enc1, enc2, enc3, enc4, i = 0;

        input = _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 += _keyStr.charAt(enc1);
            output += _keyStr.charAt(enc2);
            output += _keyStr.charAt(enc3);
            output += _keyStr.charAt(enc4);
        }
        return output;
    };

    var decode = function (input) {
        var output = "", chr1, chr2, chr3, enc1, enc2, enc3, enc4, i = 0;

        input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

        while (i < input.length) {

            enc1 = _keyStr.indexOf(input.charAt(i++));
            enc2 = _keyStr.indexOf(input.charAt(i++));
            enc3 = _keyStr.indexOf(input.charAt(i++));
            enc4 = _keyStr.indexOf(input.charAt(i++));

            chr1 = (enc1 << 2) | (enc2 >> 4);
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
            chr3 = ((enc3 & 3) << 6) | enc4;

            output += String.fromCharCode(chr1);

            if (enc3 !== 64) {
                output += String.fromCharCode(chr2);
            }
            if (enc4 !== 64) {
                output += String.fromCharCode(chr3);
            }

        }

        return _utf8_decode(output);
    };

    var decodeToHex = function(input) {
        return _hexEncode(decode(input));
    };

    var encodeFromHex = function(input) {
        return encode(_hexDecode(input));
    };

    return {
        'encode': encode,
        'decode': decode,
        'decodeToHex': decodeToHex,
        'encodeFromHex': encodeFromHex
    };
}());

- magikMaker · Answer 2

要使一个Base64编码的字符串适用于URL，您可以在JavaScript中执行类似以下方式的操作：

// if this is your Base64 encoded string
var str = 'VGhpcyBpcyBhbiBhd2Vzb21lIHNjcmlwdA=='; 

// make URL friendly:
str = str.replace(/\+/g, '-').replace(/\//g, '_').replace(/\=+$/, '');

// reverse to original encoding
str = (str + '===').slice(0, str.length + (str.length % 4));
str = str.replace(/-/g, '+').replace(/_/g, '/');

另请参见此示例：http://jsfiddle.net/magikMaker/7bjaT/

- Kathir · Answer 3

请注意，这并不适用于原始Unicode字符串！请参阅此处的Unicode部分。

编码语法 var encodedData = window.btoa(stringToEncode); 解码语法 var decodedData = window.atob(encodedData);

- Nijikokun · Answer 4

除了十六进制编码之外，我已经手动重新编写了这些编码和解码方法，采用模块化格式以实现跨平台/浏览器兼容性并使用真正的私有作用域，并且在速度上使用btoa和atob（如果存在）而不是自己的编码。

https://gist.github.com/Nijikokun/5192472

使用方法：

base64.encode(/* String */);
base64.decode(/* String */);

utf8.encode(/* String */);
utf8.decode(/* String */);

- Oded BD · Answer 5

2022 弃用警告更新

我在 vscode 上看到了弃用警告。

This function is only provided for compatibility with legacy web platform APIs and should never be used in new code, 
because they use strings to represent binary data and predate the introduction of typed arrays in JavaScript. 
For code running using Node.js APIs, 
converting between base64-encoded strings and binary data should be performed using Buffer.from(str, 'base64') andbuf.toString('base64').

在进一步搜索后，我发现这个问题说明它并没有被弃用。

https://github.com/microsoft/TypeScript/issues/45566

所以，在Web JS上消除废弃警告的解决方案是使用 window.btoa，这样警告就会消失。

- Nedudi · Answer 6

如果您需要编码HTML图像对象，您可以编写一个简单的函数，例如：

function getBase64Image(img) {
  var canvas = document.createElement("canvas");
  canvas.width = img.width;
  canvas.height = img.height;
  var ctx = canvas.getContext("2d");
  ctx.drawImage(img, 0, 0);
  var dataURL = canvas.toDataURL("image/png");
  // escape data:image prefix
  return dataURL.replace(/^data:image\/(png|jpg);base64,/, "");
  // or just return dataURL
  // return dataURL
}

通过id获取图像的Base64编码：

function getBase64ImageById(id){
  return getBase64Image(document.getElementById(id));
}

更多内容请点击这里.

- Alireza · Answer 7

You can use window.btoa and window.atob...

const encoded = window.btoa('Alireza Dezfoolian'); // encode a string
const decoded = window.atob(encoded); // decode the string

也许使用 MDN 的方式可以最好地完成你的工作...同时接受 Unicode...使用这两个简单函数：

// UCS-2 string to Base64 encoded ASCII
function utoa(str) {
    return window.btoa(unescape(encodeURIComponent(str)));
}
// Base64 encoded ASCII to UCS-2 string
function atou(str) {
    return decodeURIComponent(escape(window.atob(str)));
}
// Usage:
utoa('✓ à la mode'); // 4pyTIMOgIGxhIG1vZGU=
atou('4pyTIMOgIGxhIG1vZGU='); // "✓ à la mode"

utoa('I \u2661 Unicode!'); // SSDimaEgVW5pY29kZSE=
atou('SSDimaEgVW5pY29kZSE='); // "I ♡ Unicode!"

- Ricardo Machado · Answer 8

我需要对一段UTF-8字符串进行Base64编码，这是我的一个项目需求。大部分回答都没有正确地处理UTF-16代理对，当转换为UTF-8时会出现问题。为了完整起见，我将发布我的解决方案：

function strToUTF8Base64(str) {

    function decodeSurrogatePair(hi, lo) {
        var resultChar = 0x010000;
        resultChar += lo - 0xDC00;
        resultChar += (hi - 0xD800) << 10;
        return resultChar;
    }

    var bytes = [0, 0, 0];
    var byteIndex = 0;
    var result = [];

    function output(s) {
        result.push(s);
    }

    function emitBase64() {

        var digits =
                'ABCDEFGHIJKLMNOPQRSTUVWXYZ' +
                'abcdefghijklmnopqrstuvwxyz' +
                '0123456789+/';

        function toDigit(value) {
            return digits[value];
        }

        // --Byte 0--    --Byte 1--    --Byte 2--
        // 1111  1122    2222  3333    3344  4444

        var d1 = toDigit(bytes[0] >> 2);
        var d2 = toDigit(
            ((bytes[0] & 0x03) << 4) |
            (bytes[1] >> 4));
        var d3 = toDigit(
            ((bytes[1] & 0x0F) << 2) |
            (bytes[2] >> 6));
        var d4 = toDigit(
            bytes[2] & 0x3F);

        if (byteIndex === 1) {
            output(d1 + d2 + '==');
        }
        else if (byteIndex === 2) {
            output(d1 + d2 + d3 + '=');
        }
        else {
            output(d1 + d2 + d3 + d4);
        }
    }

    function emit(chr) {
        bytes[byteIndex++] = chr;
        if (byteIndex == 3) {
            emitBase64();
            bytes[0] = 0;
            bytes[1] = 0;
            bytes[2] = 0;
            byteIndex = 0;
        }
    }

    function emitLast() {
        if (byteIndex > 0) {
            emitBase64();
        }
    }

    // Converts the string to UTF8:

    var i, chr;
    var hi, lo;
    for (i = 0; i < str.length; i++) {
        chr = str.charCodeAt(i);

        // Test and decode surrogate pairs in the string
        if (chr >= 0xD800 && chr <= 0xDBFF) {
            hi = chr;
            lo = str.charCodeAt(i + 1);
            if (lo >= 0xDC00 && lo <= 0xDFFF) {
                chr = decodeSurrogatePair(hi, lo);
                i++;
            }
        }

        // Encode the character as UTF-8.
        if (chr < 0x80) {
            emit(chr);
        }
        else if (chr < 0x0800) {
            emit((chr >> 6) | 0xC0);
            emit(((chr >> 0) & 0x3F) | 0x80);
        }
        else if (chr < 0x10000) {
            emit((chr >> 12) | 0xE0);
            emit(((chr >>  6) & 0x3F) | 0x80);
            emit(((chr >>  0) & 0x3F) | 0x80);
        }
        else if (chr < 0x110000) {
            emit((chr >> 18) | 0xF0);
            emit(((chr >> 12) & 0x3F) | 0x80);
            emit(((chr >>  6) & 0x3F) | 0x80);
            emit(((chr >>  0) & 0x3F) | 0x80);
        }
    }

    emitLast();

    return result.join('');
}

请注意，代码并没有经过彻底测试。我已经测试了一些输入内容，包括像 strToUTF8Base64('衠衢蠩蠨') 这样的内容，并与在线编码工具(https://www.base64encode.org/)的输出进行了比较。

- Johan · Answer 9

这里提供一个压缩过的兼容性代码补丁，用于实现window.atob和window.btoa函数：

(function(){function t(t){this.message=t}var e="undefined"!=typeof exports?exports:this,r="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";t.prototype=Error(),t.prototype.name="InvalidCharacterError",e.btoa||(e.btoa=function(e){for(var o,n,a=0,i=r,c="";e.charAt(0|a)||(i="=",a%1);c+=i.charAt(63&o>>8-8*(a%1))){if(n=e.charCodeAt(a+=.75),n>255)throw new t("'btoa' failed: The string to be encoded contains characters outside of the Latin1 range.");o=o<<8|n}return c}),e.atob||(e.atob=function(e){if(e=e.replace(/=+$/,""),1==e.length%4)throw new t("'atob' failed: The string to be decoded is not correctly encoded.");for(var o,n,a=0,i=0,c="";n=e.charAt(i++);~n&&(o=a%4?64*o+n:n,a++%4)?c+=String.fromCharCode(255&o>>(6&-2*a)):0)n=r.indexOf(n);return c})})();

(function (root, factory) {
    if (typeof define === 'function' && define.amd) {
        // AMD. Register as an anonymous module.
        define([], function() {factory(root);});
    } else factory(root);
// node.js has always supported base64 conversions, while browsers that support
// web workers support base64 too, but you may never know.
})(typeof exports !== "undefined" ? exports : this, function(root) {
    if (root.atob) {
        // Some browsers' implementation of atob doesn't support whitespaces
        // in the encoded string (notably, IE). This wraps the native atob
        // in a function that strips the whitespaces.
        // The original function can be retrieved in atob.original
        try {
            root.atob(" ");
        } catch(e) {
            root.atob = (function(atob) {
                var func = function(string) {
                    return atob(String(string).replace(/[\t\n\f\r ]+/g, ""));
                };
                func.original = atob;
                return func;
            })(root.atob);
        }
        return;
    }

        // base64 character set, plus padding character (=)
    var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",
        // Regular expression to check formal correctness of base64 encoded strings
        b64re = /^(?:[A-Za-z\d+\/]{4})*?(?:[A-Za-z\d+\/]{2}(?:==)?|[A-Za-z\d+\/]{3}=?)?$/;

    root.btoa = function(string) {
        string = String(string);
        var bitmap, a, b, c,
            result = "", i = 0,
            rest = string.length % 3; // To determine the final padding

        for (; i < string.length;) {
            if ((a = string.charCodeAt(i++)) > 255
                    || (b = string.charCodeAt(i++)) > 255
                    || (c = string.charCodeAt(i++)) > 255)
                throw new TypeError("Failed to execute 'btoa' on 'Window': The string to be encoded contains characters outside of the Latin1 range.");

            bitmap = (a << 16) | (b << 8) | c;
            result += b64.charAt(bitmap >> 18 & 63) + b64.charAt(bitmap >> 12 & 63)
                    + b64.charAt(bitmap >> 6 & 63) + b64.charAt(bitmap & 63);
        }

        // If there's need of padding, replace the last 'A's with equal signs
        return rest ? result.slice(0, rest - 3) + "===".substring(rest) : result;
    };

    root.atob = function(string) {
        // atob can work with strings with whitespaces, even inside the encoded part,
        // but only \t, \n, \f, \r and ' ', which can be stripped.
        string = String(string).replace(/[\t\n\f\r ]+/g, "");
        if (!b64re.test(string))
            throw new TypeError("Failed to execute 'atob' on 'Window': The string to be decoded is not correctly encoded.");

        // Adding the padding if missing, for semplicity
        string += "==".slice(2 - (string.length & 3));
        var bitmap, result = "", r1, r2, i = 0;
        for (; i < string.length;) {
            bitmap = b64.indexOf(string.charAt(i++)) << 18 | b64.indexOf(string.charAt(i++)) << 12
                    | (r1 = b64.indexOf(string.charAt(i++))) << 6 | (r2 = b64.indexOf(string.charAt(i++)));

            result += r1 === 64 ? String.fromCharCode(bitmap >> 16 & 255)
                    : r2 === 64 ? String.fromCharCode(bitmap >> 16 & 255, bitmap >> 8 & 255)
                    : String.fromCharCode(bitmap >> 16 & 255, bitmap >> 8 & 255, bitmap & 255);
        }
        return result;
    };
});

完整版本可从https://github.com/MaxArt2501/base64-js/blob/master/base64.js获取。

- Shivaji Mutkule · Answer 10

使用js-base64库作为：

btoa()无法与表情符号一起使用

var str = "I was funny ";
console.log("Original string:", str);

var encodedStr = Base64.encode(str)
console.log("Encoded string:", encodedStr);

var decodedStr = Base64.decode(encodedStr)
console.log("Decoded string:", decodedStr);

<script src="https://cdn.jsdelivr.net/npm/js-base64@2.5.2/base64.min.js"></script>