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  3. Node.js — Convert a String to Buffer

Node.js — Convert a String to Buffer

When working with Node.js’ crypto module you sometimes need to provide Buffer instances as an argument. For example, the timingSafeEqual function accepts two buffer arguments for comparison. Sometimes your raw values are strings and you need to convert them before using them in your application code.

This tutorial shows you how to convert a string value to a buffer in Node.js.

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Create Buffer From String in Node.js

Buffers in Node.js are used to represent a fixed-length sequence of bytes. As mentioned, some of the Node.js internals work with buffers. You may need to convert your input values to buffer instances before using them.

In Node.js you can typically use the static Buffer.from() method to create a buffer from a given input value:

const buffer = Buffer.from('your string value', 'utf8')

The second argument to Buffer.from(input, encoding) is the encoding of your input value. In case you’re working with a different encoding than UTF-8, you can provide it there. Node.js supports a variety of encoding, like ascii, hex, base64, and so on.

If you want to make sure you’re properly using string inputs to create your buffers, you may build yourself a small utility function that checks the type of the input parameter: 

/**
 * Converts the given `string` value to a buffer.
 * 
 * @param {String} input
 * @param {BufferEncoding|undefined} encoding
 *
 * @returns {Buffer}
 */
function stringToBuffer(input, encoding = 'utf8') {  
  if (typeof input !== 'string') {
    throw new TypeError(`You must provide a string value to "toBuffer". Received "${typeof input}"`)
  }

  return Buffer.from(input, encoding)
}

There’s a related tutorial here on Future Studio tutorial where we walk you through the process of creating a base64-encoded string in Node.js using Buffers, too.

Enjoy buffers!

Mentioned Resources

Marcus Pöhls

Marcus is a fullstack JS developer. He’s passionate about the hapi framework for Node.js and loves to build web apps and APIs. Creator of Futureflix and the “learn hapi” learning path.

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