How to Fix "btoa is not defined" Error in Node.js?

Why Does This Happen?

Unlike in web browsers (where btoa() is a global function), in Node.js versions below 16 the btoa() function is not available in the global namespace. For this reason, when you try to access it directly, it throws a ReferenceError, for example, like in the following case:

// ReferenceError: btoa is not defined
console.log(btoa('foobar'));

How to Fix the Issue?

You can use the Buffer.from() method instead to base64-encode a string, for example, like so:

const encodedStr = Buffer.from('foobar').toString('base64');

console.log(encodedStr); // 'Zm9vYmFy'

Please note that btoa() was added to the global namespace in Node.js v16 (as legacy support). Therefore, you can also upgrade Node.js to v16+. However, it is recommended to use the Buffer.from() method for base64-encoding a string (as it can handle characters beyond the ASCII range).