您可以使用btoa()和atob()来转换base64编码。

关于这些函数接受/返回什么，评论中似乎有一些混淆，所以…

btoa() accepts a “string” where each character represents an 8-bit byte – if you pass a string containing characters that can’t be represented in 8 bits, it will probably break. This isn’t a problem if you’re actually treating the string as a byte array, but if you’re trying to do something else then you’ll have to encode it first. atob() returns a “string” where each character represents an 8-bit byte – that is, its value will be between 0 and 0xff. This does not mean it’s ASCII – presumably if you’re using this function at all, you expect to be working with binary data and not text.

参见:

如何使用Javascript和XMLHttpRequest加载二进制图像数据?

这里的大多数评论都过时了。您可能同时使用btoa()和atob()，除非您支持非常过时的浏览器。

检查:

https://caniuse.com/?search=atob https://caniuse.com/?search=btoa

在_utf8_decode的两个实现中都有一些错误。C1和c2由于var语句的错误使用被赋值为全局变量，c3根本没有初始化或声明。

它可以工作，但这些变量将覆盖该函数之外的任何具有相同名称的现有变量。

这里有一个版本不会这样做:

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

当我使用

btoa("☸☹☺☻☼☾☿"))

我得到:

InvalidCharacterError:要编码的字符串包含Latin1范围之外的字符。

我发现文档，Unicode字符串，提供了一个解决方案如下。

function toBinary(string) { const codeUnits = new Uint16Array(string.length); for (let i = 0; i < codeUnits.length; i++) { codeUnits[i] = string.charCodeAt(i); } return String.fromCharCode(...new Uint8Array(codeUnits.buffer)); } function fromBinary(binary) { const bytes = new Uint8Array(binary.length); for (let i = 0; i < bytes.length; i++) { bytes[i] = binary.charCodeAt(i); } return String.fromCharCode(...new Uint16Array(bytes.buffer)); } const myString = "☸☹☺☻☼☾☿" // console.log(btoa(myString)) // Error InvalidCharacterError: The string to be encoded contains characters outside of the Latin1 range. const converted = toBinary(myString) const encoded = btoa(converted) console.log(encoded) const decoded = atob(encoded) const original = fromBinary(decoded) console.log(original);

从下面的评论(由SET和Stefan Steiger)接受的答案，这里是一个快速总结如何编码/解码一个字符串到Base64，而不需要一个库。

str = "The quick brown fox jumps over the lazy dog";
b64 = btoa(unescape(encodeURIComponent(str)));
str = decodeURIComponent(escape(window.atob(b64)));

纯JavaScript演示

const input = document.getElementsByTagName('input')[0]; const btnConv = document.getElementById('btnConv'); const btnDeConv = document.getElementById('btnDeConv'); input.value = "The quick brown fox jumps over the lazy dog"; btnConv.addEventListener('click', () => { const txt = input.value; const b64 = btoa(unescape(encodeURIComponent(txt))); input.value = b64; btnDeConv.style.display = 'block'; btnConv.style.display = 'none'; }); btnDeConv.addEventListener('click', () => { var b64 = input.value; var txt = decodeURIComponent(escape(window.atob(b64))); input.value = txt; btnConv.style.display = 'block'; btnDeConv.style.display = 'none'; }); input{width:500px;} #btnDeConv{display:none;} <div><input type="text" /></div> <button id="btnConv">Convert</button> <button id="btnDeConv">DeConvert</button>

.

jQuery演示(使用jQuery库进行显示，但不用于编码/解码)

str = "The quick brown fox jumps over the lazy dog"; $('input').val(str); $('#btnConv').click(function(){ var txt = $('input').val(); var b64 = btoa(unescape(encodeURIComponent(txt))); $('input').val(b64); $('#btnDeConv').show(); }); $('#btnDeConv').click(function(){ var b64 = $('input').val(); var txt = decodeURIComponent(escape(window.atob(b64))); $('input').val(txt); }); #btnDeConv{display:none;} <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <input type="text" /> <button id="btnConv">Convert</button> <button id="btnDeConv">DeConvert</button>

还看到:

Base64 - MDN Web文档 在JavaScript中判断一个字符串是否在Base64中

Sunny的代码很棒，只是因为引用了“this”而在Internet Explorer 7中崩溃了。通过将这些引用替换为"Base64"来修复:

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 +
            Base64._keyStr.charAt(enc1) + Base64._keyStr.charAt(enc2) +
            Base64._keyStr.charAt(enc3) + Base64._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 = Base64._keyStr.indexOf(input.charAt(i++));
            enc2 = Base64._keyStr.indexOf(input.charAt(i++));
            enc3 = Base64._keyStr.indexOf(input.charAt(i++));
            enc4 = Base64._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;
    }
}

Internet Explorer 10+

// Define the string
var string = 'Hello World!';

// Encode the String
var encodedString = btoa(string);
console.log(encodedString); // Outputs: "SGVsbG8gV29ybGQh"

// Decode the String
var decodedString = atob(encodedString);
console.log(decodedString); // Outputs: "Hello World!"

跨浏览器

// Create Base64 Object
var Base64={_keyStr:"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",encode:function(e){var t="";var n,r,i,s,o,u,a;var f=0;e=Base64._utf8_encode(e);while(f<e.length){n=e.charCodeAt(f++);r=e.charCodeAt(f++);i=e.charCodeAt(f++);s=n>>2;o=(n&3)<<4|r>>4;u=(r&15)<<2|i>>6;a=i&63;if(isNaN(r)){u=a=64}else if(isNaN(i)){a=64}t=t+this._keyStr.charAt(s)+this._keyStr.charAt(o)+this._keyStr.charAt(u)+this._keyStr.charAt(a)}return t},decode:function(e){var t="";var n,r,i;var s,o,u,a;var f=0;e=e.replace(/[^A-Za-z0-9\+\/\=]/g,"");while(f<e.length){s=this._keyStr.indexOf(e.charAt(f++));o=this._keyStr.indexOf(e.charAt(f++));u=this._keyStr.indexOf(e.charAt(f++));a=this._keyStr.indexOf(e.charAt(f++));n=s<<2|o>>4;r=(o&15)<<4|u>>2;i=(u&3)<<6|a;t=t+String.fromCharCode(n);if(u!=64){t=t+String.fromCharCode(r)}if(a!=64){t=t+String.fromCharCode(i)}}t=Base64._utf8_decode(t);return t},_utf8_encode:function(e){e=e.replace(/\r\n/g,"\n");var t="";for(var n=0;n<e.length;n++){var r=e.charCodeAt(n);if(r<128){t+=String.fromCharCode(r)}else if(r>127&&r<2048){t+=String.fromCharCode(r>>6|192);t+=String.fromCharCode(r&63|128)}else{t+=String.fromCharCode(r>>12|224);t+=String.fromCharCode(r>>6&63|128);t+=String.fromCharCode(r&63|128)}}return t},_utf8_decode:function(e){var t="";var n=0;var r=c1=c2=0;while(n<e.length){r=e.charCodeAt(n);if(r<128){t+=String.fromCharCode(r);n++}else if(r>191&&r<224){c2=e.charCodeAt(n+1);t+=String.fromCharCode((r&31)<<6|c2&63);n+=2}else{c2=e.charCodeAt(n+1);c3=e.charCodeAt(n+2);t+=String.fromCharCode((r&15)<<12|(c2&63)<<6|c3&63);n+=3}}return t}}

// Define the string
var string = 'Hello World!';

// Encode the String
var encodedString = Base64.encode(string);
console.log(encodedString); // Outputs: "SGVsbG8gV29ybGQh"

// Decode the String
var decodedString = Base64.decode(encodedString);
console.log(decodedString); // Outputs: "Hello World!"

js小提琴

用node . js

下面是在Node.js中如何将普通文本编码为base64:

//Buffer() requires a number, array or string as the first parameter, and an optional encoding type as the second parameter.
// The default is "utf8". Possible encoding types are "ascii", "utf8", "ucs2", "base64", "binary", and "hex"
var b = Buffer.from('JavaScript');
// If we don't use toString(), JavaScript assumes we want to convert the object to utf8.
// We can make it convert to other formats by passing the encoding type to toString().
var s = b.toString('base64');

下面是解码base64编码字符串的方法:

var b = new Buffer('SmF2YVNjcmlwdA==', 'base64')
var s = b.toString();

. js和

使用dojox.encoding.base64对字节数组进行编码:

var str = dojox.encoding.base64.encode(myByteArray);

解码一个base64编码的字符串:

var bytes = dojox.encoding.base64.decode(str)

安装angular-base64

<script src="bower_components/angular-base64/angular-base64.js"></script>

angular
    .module('myApp', ['base64'])
    .controller('myController', [

    '$base64', '$scope',
    function($base64, $scope) {

        $scope.encoded = $base64.encode('a string');
        $scope.decoded = $base64.decode('YSBzdHJpbmc=');
}]);