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Edge Security Acceleration:Runtime API

Last Updated:Jun 08, 2026

Lists the Web APIs, Node APIs, and ESA-specific APIs available in Edge Function.

Web APIs

Streams

API operation

Description

References

ByteLengthQueuingStrategy

Built-in byte-length queuing strategy for stream construction.

ByteLengthQueuingStrategy

CountQueuingStrategy

Built-in chunk-counting queuing strategy for stream construction.

CountQueuingStrategy

ReadableStream

Readable stream of byte data. The Fetch API exposes a ReadableStream through the Response.body property.

ReadableStream

ReadableStreamDefaultReader

Default reader for consuming stream data from network sources such as fetch requests.

ReadableStreamDefaultReader

ReadableByteStreamController

Controls the state and internal queue of a ReadableStream.

ReadableByteStreamController

ReadableStreamBYOBReader

Reader that supports zero-copy reading from an underlying byte source for efficient data copy.

ReadableStreamBYOBReader

ReadableStreamBYOBRequest

ReadableStreamBYOBRequest

ReadableStreamDefaultController

Controls a ReadableStream's state and internal queue. Used for non-byte streams.

ReadableStreamDefaultController

WritableStream

Standard abstraction for writing streaming data to a sink, with built-in backpressure and queuing.

WritableStream

WritableStreamDefaultWriter

Returned by WritableStream.getWriter(). Locks the writer to the WritableStream so no other streams can write to the underlying sink.

WritableStreamDefaultWriter

WritableStreamDefaultController

Controls a WritableStream's state. The underlying sink receives a WritableStreamDefaultController instance during construction.

WritableStreamDefaultController

TransformStream

Transforms a data stream from one format to another. Pass it to ReadableStream.pipeThrough() to decode or encode video frames, decompress data, or convert between formats such as XML and JSON.

TransformStream

TransformStreamDefaultController

Manipulates the associated ReadableStream and WritableStream of a TransformStream. Created automatically during construction with no constructor — access it through the TransformStream() callback methods.

TransformStreamDefaultController

CompressionStream

An operation for compressing a stream of data.

CompressionStream

DecompressionStream

An operation for decompressing a stream of data.

DecompressionStream

Encoding/Decoding

API operation

Description

References

TextEncoder

Takes a stream of code points as input and emits a stream of UTF-8 bytes.

TextEncoder

TextDecoder

Decodes a byte stream into code points for a specific encoding such as UTF-8, ISO-8859-2, KOI8-R, or GBK.

TextDecoder

TextEncoderStream

Streaming equivalent of TextEncoder. Converts a string stream into UTF-8 bytes.

TextEncoderStream

TestDecoderStream

Streaming equivalent of TextDecoder. Converts a binary-encoded text stream (such as UTF-8) into strings.

TextDecoderStream

atob

Decodes a base64-encoded string.

atob

btoa

Encodes a string to base64 ASCII.

btoa

Web Crypto

API operation

Description

References

Crypto

Provides access to a cryptographically strong random number generator and cryptographic primitives.

Crypto

SubtleCrypto

Low-level cryptographic functions. Access through the crypto.subtle property.

SubtleCrypto

CryptoKey

Cryptographic key obtained from one of the SubtleCrypto methods: generateKey(), deriveKey(), importKey(), or unwrapKey().

CryptoKey

CryptoKeyPair

Key pair for an asymmetric cryptography algorithm.

CryptoKeyPair

Timers

API operation

Description

References

setInterval

Repeatedly calls a function, with a fixed time delay between each call.

setInterval

clearInterval

Cancels a timed, repeating action which was previously started by a call to setInterval().

clearInterval

setTimeout

Sets a timer which executes a function once after the delay elapses.

setTimeout

clearTimeout

Cancels a scheduled action initiated by setTimeout().

clearTimeout

Console

API operation

Description

References

Console

Debugging interface. ESA supports only console.log() for printing debug information and console.alert() for writing key information to logs.

console

URL

API operation

Description

References

URL

Parses, constructs, normalizes, and encodes URLs.

URL

URLPattern

Matches URLs or URL segments against a pattern.

URL Pattern API

Fetch

API operation

Description

References

Fetch

Starts a resource request. Returns a promise that resolves with the response.

Fetch API

Headers

Gets, sets, adds, and removes HTTP request and response headers.

Headers

Request

Creates a Request object representing a resource request.

Request

RequestInit

Options for configuring a Fetch request. Pass to the Request() constructor or the fetch() function.

RequestInit

Response

Represents a request response. Create one with the Response() constructor or receive one from API operations such as fetch().

Response

WebAssembly

API operation

Description

References

Module

Compiled, stateless WebAssembly code that can be instantiated.

WebAssembly.Module

Instance

Stateful, executable instance of a WebAssembly.Module. Contains all exported functions for calling WebAssembly from JavaScript.

WebAssembly.Instance

Node APIs

API operation

Description

References

assert

Assertion functions for verifying invariants.

assert

AsyncLocalStorage

Stores and propagates context across asynchronous operations.

AsyncLocalStorage

Buffer

Fixed-length byte sequence. One of the most common binary data processing interfaces in Node.js.

buffer

Crypto

Cryptographic functions: hash, HMAC, sign, verify, cipher, and decipher.

crypto

Diagnostics Channel

Named channels for reporting diagnostic message data.

diagnostics_channel

path

Utilities for working with file and directory paths.

path

process

Current process status data. ESA supports only the env and nextTick subinterfaces.

process

Streams

Abstract interface for processing streaming data. Provided by the node:stream module.

Streams API

StringDecoder

Decodes Buffer objects into strings.

StringDecoder

util

Node.js utility functions useful for both internal APIs and application development.

util

ESA APIs

API operation

Description

References

Cache API

Caches data on points of presence (POPs) for faster subsequent requests. Supports configurable TTL and cache size.

Cache API

KV API

Edge key-value storage. Data written to Edge KV is automatically synchronized to POPs worldwide and readable by Edge Function on the same POP.

Edge KV API

HtmlStreaming

Processes and transforms HTML streaming data on POPs. Supports chunked transmission for accelerated delivery.

HTMLStream API