Window: atob() method
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The atob() method of the Window interface decodes a
string of data which has been encoded using Base64 encoding. You can use
the Window.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.
Also consider using the Uint8Array.fromBase64() method, which creates a Uint8Array 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
encodedData-
A base64-encoded string, using the alphabet produced by
Window.btoa().
Return value
A binary string containing raw bytes decoded from encodedData. Strings in JavaScript are encoded as UTF-16, so this means each character must have a code point less than 256, representing one byte of data.
Exceptions
InvalidCharacterErrorDOMException-
Thrown if
encodedDatais not valid base64.
Examples
const encodedData = window.btoa("Hello, world"); // encode a string
const decodedData = window.atob(encodedData); // decode the string
For more examples, see the Window.btoa() method.
Specifications
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Available in workers
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Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support
See also
- A polyfill of
atobis available incore-js dataURLsWorkerGlobalScope.atob(): the same method, but in worker scopes.Window.btoa()Uint8Array.fromBase64()