How to Base64-Encode a JavaScript String?

In JavaScript, you can use the btoa() method to encode a string into its Base64 equivalent.

For example:

// ES5+
const encodedStr = btoa('foobar');
console.log(encodedStr); // 'Zm9vYmFy'

Please note that the btoa() only supports single byte (8-bit) characters in the ASCII or Latin-1 character sets.

For example, if you pass a string to the btoa() method that is not in the ASCII or Latin-1 character sets, it will throw an error:

// ES5+
// Uncaught DOMException: Failed to execute 'btoa' on 'Window': The string to be encoded contains characters outside of the Latin1 range.
btoa('🦊');

You will need to convert the string to a binary string to make it compatible with the btoa() method for Base64 encoding.