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WorkerGlobalScope: atob() method

files/en-us/web/api/workerglobalscope/atob/index.md

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{{APIRef("HTML DOM")}}{{AvailableInWorkers("worker")}}

The atob() method of the {{domxref("WorkerGlobalScope")}} interface decodes a string of data which has been encoded using {{glossary("Base64")}} encoding. You can use the {{domxref("WorkerGlobalScope.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 {{Glossary("ASCII")}} values 0 through 31.

Syntax

js-nolint
atob(encodedData)

Parameters

  • 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.

Return value

An ASCII string containing decoded data from encodedData.

Exceptions

  • InvalidCharacterError {{domxref("DOMException")}}
    • : Thrown if encodedData is not valid base64.

Examples

js
const encodedData = self.btoa("Hello, world"); // encode a string
const decodedData = self.atob(encodedData); // decode the string

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

  • A polyfill of atob is available in core-js
  • data URLs
  • {{domxref("Window.atob()")}}: the same method, but in window scopes.
  • {{domxref("WorkerGlobalScope.btoa()")}}
  • {{jsxref("Uint8Array.fromBase64()")}}