How to Base64 Decode a String in Node.js

Base64 decoding is the process of converting a Base64 encoded string back into its original plain-text form. In this article, we'll explore how to perform Base64 decoding in a Node.js application using the built-in Buffer object.

To start with, let's create a buffer from a Base64 encoding string using the `Buffer.from()` method. The second parameter of this method is optional and specifies the character encoding. If no character encoding is specified, UTF-8 will be used as the default.

Here's an example:

```

const base64 = 'QmFzZTY0IEVuY29kaW5nIGluIE5vZGUuanM=';

const buff = Buffer.from(base64, 'base64');

console.log(buff.toString()); // Output: 'Hello World'

```

As you can see, we first create a buffer from the Base64 encoding string using `Buffer.from()` and then decode it to the UTF-8 string using the `toString()` method.

The Buffer object provides several methods to perform different encoding and decoding conversions. These methods include:

* `Buffer.from()`: Creates a buffer or binary data array for the given encoding.

* `Buffer.toString()`: Decodes a buffer as a string.

* `Buffer.from()` with the second parameter set to `'base64'`: Decodes a Base64 encoded string.

Here's another example that shows how to decode a Base64 encoded string using `Buffer.from()`:

```

const str = 'Base64 Encoding in Node.js';

const buff = Buffer.from(str, 'utf-8');

console.log(buff.toString('base64')); // Output: 'QmFzZTY0IEVuY29kaW5nIGluIE5vZGUuanM='

```

In this example, we first create a buffer from the plain-text string using `Buffer.from()` and then encode it to the Base64 encoded string using the `toString('base64')` method.

The Buffer object provides many other methods for performing different encoding and decoding conversions. For example, you can use `Buffer.from()` with the second parameter set to `'ucs2'`, `'utf-16'`, or `'ascii'` to decode a buffer as UCS-2, UTF-16, or ASCII respectively.

In conclusion, Base64 decoding in Node.js is a simple process that involves creating a buffer from the Base64 encoding string using `Buffer.from()` and then decoding it to the original plain-text form using the `toString()` method. The Buffer object provides many methods for performing different encoding and decoding conversions, making it easy to work with binary data in your Node.js application.

Base64 decode js