In chromote: Headless Chrome Web Browser Interface

#| echo: false
if (!exists("MAN_PATH")) MAN_PATH <- "man"

Basic usage

This will start a headless browser and open an interactive viewer for it in a normal browser, so that you can see what the headless browser is doing.

library(chromote)

b <- ChromoteSession$new()

# In a web browser, open a viewer for the headless browser. Works best with
# Chromium-based browsers.
b$view()

The browser can be given commands, as specified by the Chrome DevTools Protocol. For example, $Browser$getVersion() (which corresponds to the Browser.getVersion in the API docs) will query the browser for version information:

b$Browser$getVersion()
#> $protocolVersion
#> [1] "1.3"
#>
#> $product
#> [1] "HeadlessChrome/98.0.4758.102"
#>
#> $revision
#> [1] "@273bf7ac8c909cde36982d27f66f3c70846a3718"
#>
#> $userAgent
#> [1] "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) HeadlessChrome/98.0.4758.102 Safari/537.36"
#>
#> $jsVersion
#> [1] "9.8.177.11"

If you have the viewer open and run the following, you'll see the web page load in the viewer[^interactive]:

b$Page$navigate("https://www.r-project.org/")

In the official Chrome DevTools Protocol (CDP) documentation, this is the Page.navigate command.

In addition to full support of the CDP, ChromoteSession objects also some convenience methods, like $screenshot(). (See the Examples section below for more information about screenshots.)

# Saves to screenshot.png
b$screenshot()

# Takes a screenshot of elements picked out by CSS selector
b$screenshot("sidebar.png", selector = ".sidebar")

[^interactive]: This simple example works interactively, but if you're using chromote to programmatically take screenshots you'll want to read vignette("example-loading-page") for a consistent and reliable approach.

chromote documentation built on April 4, 2025, 1:43 a.m.