前端:上面的解决方案很好，但后端很快……

NodeJS -不弃用

使用Buffer.from。

> inBase64 = Buffer.from('plain').toString('base64')
'cGxhaW4='

> // DEPRECATED //
> new Buffer(inBase64, 'base64').toString()
'plain'
> (node:1188987) [DEP0005] DeprecationWarning: Buffer() is deprecated due to security and usability issues. Please use the Buffer.alloc(), Buffer.allocUnsafe(), or Buffer.from() methods instead.
(Use `node --trace-deprecation ...` to show where the warning was created)

// Works //
> Buffer.from(inBase64, 'base64').toString()
'plain'

在基于Gecko/ webkit的浏览器(Firefox、Chrome和Safari)和Opera中，可以使用btoa()和atob()。

原来的答案:如何在JavaScript中将字符串编码为Base64 ?

不管怎样，我从其他答案中得到了启发，写了一个小实用程序，调用特定于平台的api，从Node.js或浏览器中普遍使用:

/** * Encode a string of text as base64 * * @param data The string of text. * @returns The base64 encoded string. */ function encodeBase64(data: string) { if (typeof btoa === "function") { return btoa(data); } else if (typeof Buffer === "function") { return Buffer.from(data, "utf-8").toString("base64"); } else { throw new Error("Failed to determine the platform specific encoder"); } } /** * Decode a string of base64 as text * * @param data The string of base64 encoded text * @returns The decoded text. */ function decodeBase64(data: string) { if (typeof atob === "function") { return atob(data); } else if (typeof Buffer === "function") { return Buffer.from(data, "base64").toString("utf-8"); } else { throw new Error("Failed to determine the platform specific decoder"); } }

在Node.js中，我们可以用简单的方式做到这一点

var base64 = 'SGVsbG8gV29ybGQ='
var base64_decode = new Buffer(base64, 'base64').toString('ascii');

console.log(base64_decode); // "Hello World"

短而快速的Base64 JavaScript解码函数没有Failsafe:

function decode_base64 (s)
{
    var e = {}, i, k, v = [], r = '', w = String.fromCharCode;
    var n = [[65, 91], [97, 123], [48, 58], [43, 44], [47, 48]];

    for (z in n)
    {
        for (i = n[z][0]; i < n[z][1]; i++)
        {
            v.push(w(i));
        }
    }
    for (i = 0; i < 64; i++)
    {
        e[v[i]] = i;
    }

    for (i = 0; i < s.length; i+=72)
    {
        var b = 0, c, x, l = 0, o = s.substring(i, i+72);
        for (x = 0; x < o.length; x++)
        {
            c = e[o.charAt(x)];
            b = (b << 6) + c;
            l += 6;
            while (l >= 8)
            {
                r += w((b >>> (l -= 8)) % 256);
            }
         }
    }
    return r;
}

PHP .js项目有很多PHP函数的JavaScript实现。包括Base64_encode和base64_decode。