JavaScript - Base64 encode and decode

In this article, we would like to show you how to encode and decode Base64 in JavaScript.

Quick solution:

// ONLINE-RUNNER:browser;

const text = 'some text...';

const encoded = btoa(text);
console.log('Encoded text: ' + encoded);  // c29tZSB0ZXh0Li4u

const decoded = atob(encoded);
console.log('Decoded text: ' + decoded);  // some text...

1. Encode

In this example, we use btoa() method to create a Base64-encoded ASCII string.

// ONLINE-RUNNER:browser;

const text = 'some text...';

const encoded = btoa(text);
console.log(encoded);  // c29tZSB0ZXh0Li4u

Output:

c29tZSB0ZXh0Li4u

2. Decode

In this example, we use atob() method to decode a string of data which has been encoded using Base64 encoding.

// ONLINE-RUNNER:browser;

const encoded = 'c29tZSB0ZXh0Li4u';

const decoded = atob(encoded);
console.log(decoded);  // some text...

Output:

some text...

References

1. atob() - Web APIs | MDN
2. btoa() - Web APIs | MDN