Chromote: Chromote class

In chromote: Headless Chrome Web Browser Interface

Chromote class

Description

A Chromote object represents the browser as a whole, and it can have multiple targets, which each represent a browser tab. In the Chrome DevTools Protocol, each target can have one or more debugging sessions to control it. A ChromoteSession object represents a single session.

A Chromote object can have any number of ChromoteSession objects as children. It is not necessary to create a Chromote object manually. You can simply call:

b <- ChromoteSession$new()

and it will automatically create a Chromote object if one has not already been created. The chromote package will then designate that Chromote object as the default Chromote object for the package, so that any future calls to ChromoteSession$new() will automatically use the same Chromote. This is so that it doesn't start a new browser for every ChromoteSession object that is created.

Public fields

default_timeout

Default timeout in seconds for chromote to wait for a Chrome DevTools Protocol response.

protocol

Dynamic protocol implementation. For expert use only!

Methods

Public methods

• Chromote$new()

• Chromote$connect()

• Chromote$view()

• Chromote$get_auto_events()

• Chromote$get_child_loop()

• Chromote$wait_for()

• Chromote$new_session()

• Chromote$get_sessions()

• Chromote$register_session()

• Chromote$send_command()

• Chromote$invoke_event_callbacks()

• Chromote$debug_messages()

• Chromote$debug_log()

• Chromote$url()

• Chromote$is_active()

• Chromote$is_alive()

• Chromote$check_active()

• Chromote$get_browser()

• Chromote$close()

• Chromote$print()

---

Method new()

Usage

Chromote$new(browser = Chrome$new(), multi_session = TRUE, auto_events = TRUE)

Arguments

browser

A Browser object

multi_session

Should multiple sessions be allowed?

auto_events

If TRUE, enable automatic event enabling/disabling; if FALSE, disable automatic event enabling/disabling.

---

Method connect()

Re-connect the websocket to the browser. The Chrome browser automatically closes websockets when your computer goes to sleep; you can use this to bring it back to life with a new connection.

Usage

Chromote$connect(multi_session = TRUE, wait_ = TRUE)

Arguments

multi_session

Should multiple sessions be allowed?

wait_

If FALSE, return a promise; if TRUE wait until connection is complete.

---

Method view()

Display the current session in the browser

If a Chrome browser is being used, this method will open a new tab using your Chrome browser. When not using a Chrome browser, set options(browser=) to change the default behavior of browseURL().

Usage

Chromote$view()

---

Method get_auto_events()

auto_events value.

For internal use only.

Usage

Chromote$get_auto_events()

---

Method get_child_loop()

Local later loop.

For expert async usage only.

Usage

Chromote$get_child_loop()

---

Method wait_for()

Wait until the promise resolves

Blocks the R session until the promise (p) is resolved. The loop from ⁠$get_child_loop()⁠ will only advance just far enough for the promise to resolve.

Usage

Chromote$wait_for(p)

Arguments

p

A promise to resolve.

---

Method new_session()

Create a new tab / window

Usage

Chromote$new_session(width = 992, height = 1323, targetId = NULL, wait_ = TRUE)

Arguments

width, height

Width and height of the new window.

targetId

Target ID of an existing target to attach to. When a targetId is provided, the width and height arguments are ignored. If NULL (the default) a new target is created and attached to, and the width and height arguments determine its viewport size.

wait_

If FALSE, return a promises::promise() of a new ChromoteSession object. Otherwise, block during initialization, and return a ChromoteSession object directly.

---

Method get_sessions()

Retrieve all ChromoteSession objects

Usage

Chromote$get_sessions()

Returns

A list of ChromoteSession objects

---

Method register_session()

Register ChromoteSession object

Usage

Chromote$register_session(session)

Arguments

session

A ChromoteSession object

For internal use only.

---

Method send_command()

Send command through Chrome DevTools Protocol.

For expert use only.

Usage

Chromote$send_command(
  msg,
  callback = NULL,
  error = NULL,
  timeout = NULL,
  sessionId = NULL
)

Arguments

msg

A JSON-serializable list containing method, and params.

callback

Method to run when the command finishes successfully.

error

Method to run if an error occurs.

timeout

Number of milliseconds for Chrome DevTools Protocol execute a method.

sessionId

Determines which ChromoteSession with the corresponding to send the command to.

---

Method invoke_event_callbacks()

Immediately call all event callback methods.

For internal use only.

Usage

Chromote$invoke_event_callbacks(event, params)

Arguments

event

A single event string

params

A list of parameters to pass to the event callback methods.

---

Method debug_messages()

Enable or disable message debugging

If enabled, R will print out the

Usage

Chromote$debug_messages(value = NULL)

Arguments

value

If TRUE, enable debugging. If FALSE, disable debugging.

---

Method debug_log()

Submit debug log message

Examples

b <- ChromoteSession$new()
b$parent$debug_messages(TRUE)
b$Page$navigate("https://www.r-project.org/")
#> SEND {"method":"Page.navigate","params":{"url":"https://www.r-project.org/"}| __truncated__}
# Turn off debug messages
b$parent$debug_messages(FALSE)

Usage

Chromote$debug_log(...)

Arguments

...

Arguments pasted together with paste0(..., collapse = "").

---

Method url()

Create url for a given path

Usage

Chromote$url(path = NULL)

Arguments

path

A path string to append to the host and port

---

Method is_active()

Is there an active websocket connection to the browser process?

Usage

Chromote$is_active()

---

Method is_alive()

Is the underlying browser process running?

Usage

Chromote$is_alive()

---

Method check_active()

Check that a chromote instance is active and alive. Will automatically reconnect if browser process is alive, but there's no active web socket connection.

Usage

Chromote$check_active()

---

Method get_browser()

Retrieve Browser' object

Usage

Chromote$get_browser()

---

Method close()

Close the Browser object

Usage

Chromote$close()

---

Method print()

Summarise the current state of the object.

Usage

Chromote$print(..., verbose = FALSE)

Arguments

...

Passed on to format() when verbose = TRUE

verbose

The print method defaults to a brief summary of the most important debugging info; use verbose = TRUE tp see the complex R6 object.

chromote documentation built on Sept. 11, 2024, 7:21 p.m.