Uint8Array Global Method Support

React Native for Kepler provides native implementations of Uint8Array static and instance methods as listed in MDN web docs to support efficient binary data encoding and decoding.

Working with binary data is a common requirement in many applications. React Native for Kepler provides optimized methods for converting between binary data (Uint8Array) and string representations (base64 and hexadecimal).

These methods are added to the global Uint8Array object and are available throughout your application without requiring any imports.

Key Features

• Efficient binary-to-string conversions: Convert binary data to and from base64 and hexadecimal strings
• Native implementation: Methods are optimized for performance using native code
• Standard compatibility: Fully compatible with the standard JavaScript Uint8Array API

Common use cases

Static Methods

Uint8Array.fromBase64(string)

Creates a new Uint8Array from a base64-encoded string.

static fromBase64(base64String: string): Uint8Array

Parameters:

• base64String: A string containing base64-encoded data

Returns: A new Uint8Array containing the decoded data

Example:

const data = Uint8Array.fromBase64('SGVsbG8gV29ybGQ=');
console.log(data); // Uint8Array representing "Hello World"

Uint8Array.fromHex(string)

Creates a new Uint8Array from a hexadecimal string.

static fromHex(hexString: string): Uint8Array

Parameters:

• hexString: A string containing hexadecimal data (must have an even length and contain only valid hex characters)

Returns:

A new Uint8Array containing the decoded data

Example:

const data = Uint8Array.fromHex('48656c6c6f20576f726c64');
console.log(data); // Uint8Array representing "Hello World"

Instance Methods

Uint8Array.prototype.toBase64()

Converts the Uint8Array to a base64-encoded string.

toBase64(): string

Returns:

A base64-encoded string representing the binary data

Example:

const array = new Uint8Array([
  72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100
]);
const base64 = array.toBase64();
console.log(base64); // "SGVsbG8gV29ybGQ="

Uint8Array.prototype.toHex()

Converts the Uint8Array to a hexadecimal string.

toHex(): string

Returns:

A hexadecimal string representing the binary data

Example:

const array = new Uint8Array([
  72, 101, 108, 108, 111, 32, 87, 111, 114, 108, 100
]);
const hex = array.toHex();
console.log(hex); // "48656c6c6f20576f726c64"

Uint8Array.prototype.setFromBase64(string)

Populates the Uint8Array with data from a base64-encoded string.

setFromBase64(base64String: string): {read: number, written: number}

Parameters:

• base64String: A string containing base64-encoded data

Returns:

An object with:

• read: Number of characters read from the input string
• written: Number of bytes written to the Uint8Array

Example:

const array = new Uint8Array(20);
const result = array.setFromBase64('SGVsbG8gV29ybGQ=');
console.log(result); // { read: 16, written: 11 }
console.log(array); // Uint8Array containing "Hello World" followed by zeros

Uint8Array.prototype.setFromHex(string)

Populates the Uint8Array with data from a hexadecimal string.

setFromHex(hexString: string): {read: number, written: number}

Parameters:

• hexString: A string containing hexadecimal data (must have an even length and contain only valid hex characters)

Returns:

An object with:

• read: Number of characters read from the input string
• written: Number of bytes written to the Uint8Array

Example:

const array = new Uint8Array(20);
const result = array.setFromHex('48656c6c6f20576f726c64');
console.log(result); // { read: 22, written: 11 }
console.log(array); // Uint8Array containing "Hello World" followed by zeros

Troubleshooting

• Only the standard base64 alphabet is supported (no base64url variant).
• Hexadecimal strings must have an even length and contain only valid hex characters (0-9, A-F, a-f).

Additional Resources

MDN Web Docs

Last updated: Sep 30, 2025