The atob() function decodes a string of data which has been encoded using Base64 encoding. You can use the btoa() method to encode and transmit data which may otherwise cause communication problems, then transmit it and use the atob() method to decode the data again. For example, you can encode, transmit, and decode control characters such as ASCII values 0 through 31.
For use with arbitrary Unicode strings, see The "Unicode Problem" section of the Base64 glossary entry.
js
atob(encodedData)
encodedData
A binary string (i.e., a string in which each character in the string is treated as a byte of binary data) containing base64-encoded data.
An ASCII string containing decoded data from encodedData.
InvalidCharacterError DOMException
Thrown if encodedData is not valid base64.
js
const encodedData = btoa("Hello, world"); // encode a string
const decodedData = atob(encodedData); // decode the string
| Specification |
|---|
| HTML Standard # dom-atob-dev |
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
atob |
4 | 12 | 1 | 10 | 10.5 | 3 | ≤37 | 18 | 4 | 11 | 1 | 1.0 |
worker_support |
30 | 12 | 4 | 10 | 17 | 10 | 4.4 | 30 | 4 | 18 | 10 | 2.0 |
atob is available in core-jsdata URLsbtoa()© 2005–2023 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/atob