Newly available Useful whenever your code regularly converts binary payloads into text-safe encodings or back again.

Uint8Array base64 and hex conversion

The Uint8Array.fromBase64() static method creates a new Uint8Array object from a base64-encoded string.

This method should be preferred over Window.atob() because it results in a byte array, which is easier to work with than a string containing raw bytes, unless your decoded binary data is actually intended to be ASCII text. If you already have an array buffer allocated and you want to populate it, use the instance method Uint8Array.prototype.setFromBase64() instead.

Binary dataEncodingTyped arrays

Browser support

Feature Desktop Mobile
Chrome
Edge
Firefox
Safari
Chrome Android
Safari iOS
javascript.builtins.Uint8Array.fromBase64
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Built-in object
Uint8Array.fromHex

The Uint8Array.fromHex() static method creates a new Uint8Array object from a hexadecimal string.
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Uint8Array.setFromBase64

The setFromBase64() method of Uint8Array instances populates this Uint8Array object with bytes from a base64-encoded string, returning an object indicating how many bytes were read and written.
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Uint8Array.setFromHex

The setFromHex() method of Uint8Array instances populates this Uint8Array object with bytes from a hex-encoded string, returning an object indicating how many bytes were read and written.
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Uint8Array.toBase64

The toBase64() method of Uint8Array instances returns a base64-encoded string based on the data in this Uint8Array object.
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Uint8Array.toHex

The toHex() method of Uint8Array instances returns a hex-encoded string based on the data in this Uint8Array object.
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1+Supported (version) Not supported ※Has note Sub-feature descriptions sourced from MDN Web Docs (CC BY-SA 2.5)

Syntax

JAVASCRIPT 
// Base64 → Uint8Array
const bytes = Uint8Array.fromBase64('SGVsbG8=');
// Uint8Array [72, 101, 108, 108, 111]

// Uint8Array → Base64
bytes.toBase64(); // 'SGVsbG8='

// Hex conversion
bytes.toHex(); // '48656c6c6f'

Live demo

Check base64 helpers

Inspect whether Uint8Array base64 helpers are present in the runtime.

JavaScript
Output
Press the Run button

Encode bytes when supported

Use toBase64 and toHex if the proposal is implemented.

JavaScript
Output
Press the Run button

Compare with TextEncoder

Start from a string and convert it into bytes before encoding.

JavaScript
Output
Press the Run button

Use cases

  • Token and key encoding

    Represent binary material as base64 or hex when logging, storing, or transmitting through text-based channels.

  • Binary message handling

    Convert between byte arrays and encoded payloads without handwritten utility code.

Cautions

  • Encoding conversions are still data transformations, so validate formats and error handling carefully.
  • Keep an eye on memory usage when converting large buffers into large strings.

Accessibility

  • No direct accessibility effect, but simpler binary handling can reduce bugs in media or document workflows.
  • If encoded output is shown to users, label it clearly because raw base64 or hex is not self-explanatory.

Related links