Window: atob() method
BaselineWidely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
Theatob() method of theWindow interface decodes astring of data which has been encoded usingBase64 encoding. You can usetheWindow.btoa() method to encode and transmitdata which may otherwise cause communication problems, then transmit it and use theatob() method to decode the data again. For example, you can encode,transmit, and decode control characters such asASCII values 0 through 31.
Also consider using theUint8Array.fromBase64() method, which creates aUint8Array object from a base64-encoded string. It results in a byte array, which is easier to work with than a string containing raw bytes.
Syntax
atob(encodedData)Parameters
encodedDataA base64-encoded string, using the alphabet produced by
Window.btoa().
Return value
A binary string containing raw bytes decoded fromencodedData. Strings in JavaScript are encoded asUTF-16, so this means each character must have a code point less than 256, representing one byte of data.
Exceptions
InvalidCharacterErrorDOMExceptionThrown if
encodedDatais not valid base64.
Examples
const encodedData = window.btoa("Hello, world"); // encode a stringconst decodedData = window.atob(encodedData); // decode the stringFor more examples, see theWindow.btoa() method.
Specifications
| Specification |
|---|
| HTML # dom-atob-dev |
Browser compatibility
See also
- A polyfill of
atobis available incore-js dataURLsWorkerGlobalScope.atob(): the same method, but in worker scopes.Window.btoa()Uint8Array.fromBase64()