JavaScript API
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JavaScript API

The list of k6 modules natively supported in your k6 scripts.

Init context

Before the k6 starts the test logic, code in the init context prepares the script. A few functions are available only in init context. For details about the runtime, refer to the Test lifecycle.

FunctionDescription
open( filePath, [mode] )Opens a file and reads all the contents into memory.

import.meta

import.meta is only available in ECMAScript modules, but not CommonJS ones.

FunctionDescription
import.meta.resolveresolve path to URL the same way that an ESM import would

k6

The k6 module contains k6-specific functionality.

FunctionDescription
check(val, sets, [tags])Runs one or more checks on a value and generates a pass/fail result but does not throw errors or otherwise interrupt execution upon failure.
fail([err])Throws an error, failing and aborting the current VU script iteration immediately.
group(name, fn)Runs code inside a group. Used to organize results in a test.
randomSeed(int)Set seed to get a reproducible pseudo-random number using Math.random.
sleep(t)Suspends VU execution for the specified duration.

k6/browser

The k6/browser module provides browser-level APIs to interact with browsers and collect frontend performance metrics as part of your k6 tests.

MethodDescription
browser.closeContext()Closes the current BrowserContext.
browser.context()Returns the current BrowserContext.
browser.isConnected Indicates whether the CDP connection to the browser process is active or not.
browser.newContext([options]) Creates and returns a new BrowserContext.
browser.newPage([options]) Creates a new Page in a new BrowserContext and returns the page. Pages that have been opened ought to be closed using Page.close. Pages left open could potentially distort the results of Web Vital metrics.
browser.version()Returns the browser application’s version.
k6 ClassDescription
BrowserContext Enables independent browser sessions with separate Pages, cache, and cookies.
ElementHandle Represents an in-page DOM element.
Frame Access and interact with the Page.’s Frames.
JSHandleRepresents an in-page JavaScript object.
KeyboardUsed to simulate the keyboard interactions with the associated Page.
LocatorThe Locator API makes it easier to work with dynamically changing elements.
MouseUsed to simulate the mouse interactions with the associated Page.
Page Provides methods to interact with a single tab in a browser.
Request Used to keep track of the request the Page makes.
Response Represents the response received by the Page.
TouchscreenUsed to simulate touch interactions with the associated Page.
WorkerRepresents a WebWorker.

k6/crypto

The k6/crypto module provides common hashing functionality available in the GoLang crypto package.

FunctionDescription
createHash(algorithm)Create a Hasher object, allowing the user to add data to hash multiple times, and extract hash digests along the way.
createHMAC(algorithm, secret)Create an HMAC hashing object, allowing the user to add data to hash multiple times, and extract hash digests along the way.
hmac(algorithm, secret, data, outputEncoding)Use HMAC to sign an input string.
md4(input, outputEncoding)Use MD4 to hash an input string.
md5(input, outputEncoding)Use MD5 to hash an input string.
randomBytes(int)Return an array with a number of cryptographically random bytes.
ripemd160(input, outputEncoding)Use RIPEMD-160 to hash an input string.
sha1(input, outputEncoding)Use SHA-1 to hash an input string.
sha256(input, outputEncoding)Use SHA-256 to hash an input string.
sha384(input, outputEncoding)Use SHA-384 to hash an input string.
sha512(input, outputEncoding)Use SHA-512 to hash an input string.
sha512_224(input, outputEncoding)Use SHA-512/224 to hash an input string.
sha512_256(input, outputEncoding)Use SHA-512/256 to hash an input string.
ClassDescription
HasherObject returned by crypto.createHash(). It allows adding more data to be hashed and to extract digests along the way.

k6/data

The k6/data module provides helpers to work with data.

Class/MethodDescription
SharedArrayread-only array like structure that shares memory between VUs

k6/encoding

The k6/encoding module provides base64 encoding/decoding as defined by RFC4648.

FunctionDescription
b64decode(input, [encoding], [format])Base64 decode a string.
b64encode(input, [encoding])Base64 encode a string.

k6/execution

The k6/execution module provides the capability to get information about the current test execution state inside the test script. You can read in your script the execution state during the test execution and change your script logic based on the current state.

k6/execution provides the test execution information with the following properties:

k6/experimental

k6/experimental modules are stable modules that may introduce breaking changes. Once they become fully stable, they may graduate to become k6 core modules.

ModulesDescription
csvProvides support for efficient and convenient parsing of CSV files.
fsProvides a memory-efficient way to handle file interactions within your test scripts.
redisFunctionality to interact with Redis.
streamsProvides an implementation of the Streams API specification, offering support for defining and consuming readable streams.
webcryptoImplements the WebCrypto API.
websocketsImplements the browser’s WebSocket API.

k6/html

The k6/html module contains functionality for HTML parsing.

FunctionDescription
parseHTML(src)Parse an HTML string and populate a Selection object.
ClassDescription
ElementAn HTML DOM element as returned by the Selection API.
SelectionA jQuery-like API for accessing HTML DOM elements.

k6/http

The k6/http module contains functionality for performing HTTP transactions.

FunctionDescription
batch( requests )Issue multiple HTTP requests in parallel (like e.g. browsers tend to do).
cookieJar()Get active HTTP Cookie jar.
del( url, [body], [params] )Issue an HTTP DELETE request.
file( data, [filename], [contentType] )Create a file object that is used for building multi-part requests.
get( url, [params] )Issue an HTTP GET request.
head( url, [params] )Issue an HTTP HEAD request.
options( url, [body], [params] )Issue an HTTP OPTIONS request.
patch( url, [body], [params] )Issue an HTTP PATCH request.
post( url, [body], [params] )Issue an HTTP POST request.
put( url, [body], [params] )Issue an HTTP PUT request.
request( method, url, [body], [params] )Issue any type of HTTP request.
asyncRequest( method, url, [body], [params] )Issue any type of HTTP request asynchronously.
setResponseCallback(expectedStatuses)Sets a response callback to mark responses as expected.
url`url`Creates a URL with a name tag. Read more on URL Grouping.
expectedStatuses( statusCodes )Create a callback for setResponseCallback that checks status codes.
ClassDescription
CookieJarUsed for storing cookies, set by the server and/or added by the client.
FileDataUsed for wrapping data representing a file when doing multipart requests (file uploads).
ParamsUsed for setting various HTTP request-specific parameters such as headers, cookies, etc.
ResponseReturned by the http.* methods that generate HTTP requests.

k6/metrics

The k6/metrics module provides functionality to create custom metrics of various types.

Metric typeDescription
CounterA metric that cumulatively sums added values.
GaugeA metric that stores the min, max and last values added to it.
RateA metric that tracks the percentage of added values that are non-zero.
TrendA metric that calculates statistics on the added values (min, max, average, and percentiles).

k6/net/grpc

The k6/net/grpc module provides a gRPC client for Remote Procedure Calls (RPC) over HTTP/2.

Class/MethodDescription
ClientgRPC client used for making RPC calls to a gRPC Server.
Client.load(importPaths, …protoFiles)Loads and parses the given protocol buffer definitions to be made available for RPC requests.
Client.connect(address [,params])Connects to a given gRPC service.
Client.invoke(url, request [,params])Makes an unary RPC for the given service/method and returns a Response.
Client.asyncInvoke(url, request [,params])Asynchronously makes an unary RPC for the given service/method and returns a Promise with Response.
Client.close()Close the connection to the gRPC service.
ParamsRPC Request specific options.
ResponseReturned by RPC requests.
ConstantsDefine constants to distinguish between gRPC Response statuses.
Stream(client, url, [,params])Creates a new gRPC stream.
Stream.on(event, handler)Adds a new listener to one of the possible stream events.
Stream.write(message)Writes a message to the stream.
Stream.end()Signals to the server that the client has finished sending.
EventHandlerThe function to call for various events on the gRPC stream.
MetadataThe metadata of a gRPC stream’s message.

k6/secrets

The k6/secrets module gives access to secrets provided by configured secret sources.

PropertyDescription
get([String])asynchrounsly get a secret from the default secret source
source([String])returns a source for the provided name that can than be used to get a secret from a concrete source

k6/timers

The k6/timers module implements timers to work with k6’s event loop. They mimic the functionality found in browsers and other JavaScript runtimes.

FunctionDescription
setTimeoutSets a function to be run after a given timeout.
clearTimeoutClears a previously set timeout with setTimeout.
setIntervalSets a function to be run on a given interval.
clearIntervalClears a previously set interval with setInterval.

Note

The timer methods are available globally, so you can use them in your script without including an import statement.

k6/ws

The k6/ws module provides a WebSocket client implementing the WebSocket protocol.

FunctionDescription
connect( url, params, callback )Create a WebSocket connection, and provides a Socket client to interact with the service. The method blocks the test finalization until the connection is closed.
Class/MethodDescription
ParamsUsed for setting various WebSocket connection parameters such as headers, cookie jar, compression, etc.
SocketWebSocket client used to interact with a WS connection.
Socket.close()Close the WebSocket connection.
Socket.on(event, callback)Set up an event listener on the connection for any of the following events:
- open
- binaryMessage
- message
- ping
- pong
- close
- error.
Socket.ping()Send a ping.
Socket.send(data)Send string data.
Socket.sendBinary(data)Send binary data.
Socket.setInterval(callback, interval)Call a function repeatedly at certain intervals, while the connection is open.
Socket.setTimeout(callback, period)Call a function with a delay, if the connection is open.

crypto

The crypto module provides a WebCrypto API implementation.

Class/MethodDescription
getRandomValuesFills the passed TypedArray with cryptographically sound random values.
randomUUIDReturns a randomly generated, 36 character long v4 UUID.
subtleThe SubtleCrypto interface provides access to common cryptographic primitives, such as hashing, signing, encryption, or decryption.

Note

The crypto object is available globally, so you can use it in your script without including an import statement.

Error codes

The following specific error codes are currently defined:

  • 1000: A generic error that isn’t any of the ones listed below.
  • 1010: A non-TCP network error - this is a place holder there is no error currently known to trigger it.
  • 1020: An invalid URL was specified.
  • 1050: The HTTP request has timed out.
  • 1100: A generic DNS error that isn’t any of the ones listed below.
  • 1101: No IP for the provided host was found.
  • 1110: Blacklisted IP was resolved or a connection to such was tried to be established.
  • 1111: Blacklisted hostname using The Block Hostnames option.
  • 1200: A generic TCP error that isn’t any of the ones listed below.
  • 1201: A “broken pipe” on write - the other side has likely closed the connection.
  • 1202: An unknown TCP error - We got an error that we don’t recognize but it is from the operating system and has errno set on it. The message in error includes the operation(write,read) and the errno, the OS, and the original message of the error.
  • 1210: General TCP dial error.
  • 1211: Dial timeout error - the timeout for the dial was reached.
  • 1212: Dial connection refused - the connection was refused by the other party on dial.
  • 1213: Dial unknown error.
  • 1220: Reset by peer - the connection was reset by the other party, most likely a server.
  • 1300: General TLS error
  • 1310: Unknown authority - the certificate issuer is unknown.
  • 1311: The certificate doesn’t match the hostname.
  • 1400 to 1499: error codes that correspond to the HTTP 4xx status codes for client errors
  • 1500 to 1599: error codes that correspond to the HTTP 5xx status codes for server errors
  • 1600: A generic HTTP/2 error that isn’t any of the ones listed below.
  • 1610: A general HTTP/2 GoAway error.
  • 1611 to 1629: HTTP/2 GoAway errors with the value of the specific HTTP/2 error code added to 1611.
  • 1630: A general HTTP/2 stream error.
  • 1631 to 1649: HTTP/2 stream errors with the value of the specific HTTP/2 error code added to 1631.
  • 1650: A general HTTP/2 connection error.
  • 1651 to 1669: HTTP/2 connection errors with the value of the specific HTTP/2 error code added to 1651.
  • 1701: Decompression error.

Read more about Error codes.

jslib

jslib is a collection of JavaScript libraries maintained by the k6 team that can be used in k6 scripts.

LibraryDescription
awsLibrary allowing to interact with Amazon AWS services
httpxWrapper around k6/http to simplify session handling
k6chaijsBDD assertion style
http-instrumentation-pyroscopeLibrary to instrument k6/http to send baggage headers for pyroscope to read back
http-instrumentation-tempoLibrary to instrument k6/http to send tracing data
utilsSmall utility functions useful in every day load testing