Implementation:Puppeteer Puppeteer Encoding

Property	Value
sources	packages/puppeteer-core/src/util/encoding.ts
domains	Utility, Binary Encoding
last_updated	2026-02-12 00:00 GMT

Overview

Description

The encoding module provides utility functions for converting between strings, base64-encoded data, and Uint8Array typed arrays. These functions are used throughout Puppeteer for handling binary data received from the Chrome DevTools Protocol, such as screenshots (PNG/JPEG), PDF content, and network response bodies, which are transmitted as base64-encoded strings.

The module exports four functions:

• stringToTypedArray -- Converts a string into a Uint8Array. When base64Encoded is true, it decodes the base64 string using the best available method: Uint8Array.fromBase64 (modern runtimes), Buffer.from (Node.js), or atob (fallback). When false, it uses TextEncoder to encode UTF-8.
• stringToBase64 -- Encodes a plain UTF-8 string to base64 by first encoding it to a Uint8Array via TextEncoder and then converting to base64.
• typedArrayToBase64 -- Converts a Uint8Array to a base64 string. It processes the array in chunks of 65,534 bytes to avoid exceeding the V8 argument limit for String.fromCodePoint.
• mergeUint8Arrays -- Concatenates multiple Uint8Array instances into a single contiguous array.

Usage

These functions are used internally when Puppeteer receives binary data over the protocol (e.g., screenshot data, PDF bytes) or needs to send binary payloads. They are not part of the public API.

Code Reference

Source Location

packages/puppeteer-core/src/util/encoding.ts

Signature

export function stringToTypedArray(
  string: string,
  base64Encoded?: boolean,
): Uint8Array;

export function stringToBase64(str: string): string;

export function typedArrayToBase64(typedArray: Uint8Array): string;

export function mergeUint8Arrays(items: Uint8Array[]): Uint8Array;

Import

import {stringToTypedArray, stringToBase64, typedArrayToBase64, mergeUint8Arrays} from '../util/encoding.js';

I/O Contract

Function	Parameter	Type	Description
stringToTypedArray	string	string	The input string (plain text or base64-encoded)
stringToTypedArray	base64Encoded	boolean	Whether the input is base64-encoded (default: false)
stringToBase64	str	string	A plain UTF-8 string to encode
typedArrayToBase64	typedArray	Uint8Array	A typed array to encode as base64
mergeUint8Arrays	items	Uint8Array[]	An array of typed arrays to concatenate

Function	Return Type	Description
stringToTypedArray	Uint8Array	The decoded or encoded byte array
stringToBase64	string	The base64-encoded string
typedArrayToBase64	string	The base64-encoded string representation
mergeUint8Arrays	Uint8Array	A single concatenated typed array

Usage Examples

// Decode a base64 screenshot from CDP
const base64Data = 'iVBORw0KGgoAAAANSUhEUgAA...';
const imageBytes = stringToTypedArray(base64Data, true);

// Encode a string to base64 for protocol transmission
const encoded = stringToBase64('Hello, Puppeteer!');

// Merge multiple response chunks into a single buffer
const merged = mergeUint8Arrays([chunk1, chunk2, chunk3]);

Related Pages

• Environment:Puppeteer_Puppeteer_Node_18_Runtime