Choosing which Chrome-based browser to use
In chromote: Headless Chrome Web Browser Interface

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

Use any version of Chrome or `chrome-headless-shell` with chromote

By default, chromote uses the Chrome browser installed on your system. Modern browsers automatically and frequently update, which is convenient for you when you're browsing the Internet but can easily introduce breaking and unexpected changes in your automations.

The chromote package allows you to download and use any version of Chrome or chrome-headless-shell available via the Google Chrome for Testing service.

To get started, call local_chrome_version() with a specific version and binary choice at the start of your script, before you create a new ChromoteSession:

library(chromote)

local_chrome_version("latest-stable", binary = "chrome")
#> ℹ Downloading `chrome` version 134.0.6998.88 for mac-arm64
#> trying URL 'https://storage.googleapis.com/chrome-for-testing-public/134.0.6998.88/mac-arm64/chrome-mac-arm64.zip'
#> Content type 'application/zip' length 158060459 bytes (150.7 MB)
#> ==================================================
#> downloaded 150.7 MB
#> 
#> ✔ Downloading `chrome` version 134.0.6998.88 for mac-arm64 [5.3s]
#> chromote will now use version 134.0.6998.88 of `chrome` for mac-arm64.

b <- ChromoteSession$new()

By default, local_chrome_version() uses the latest stable version of Chrome, matching the arguments shown in the code example above.

For scripts with a longer life span and to ensure reproducibility, you can specify a specific version of Chrome or chrome-headless-shell:

local_chrome_version("134.0.6998.88", binary = "chrome-headless-shell")
#> chromote will now use version 134.0.6998.88 of `chrome-headless-shell` for mac-arm64.

If you don't already have a copy of the requested version of the binary, local_chrome_version() will download it for you so you'll only need to download the binary once. You can list all of the versions and binaries you've installed with chrome_versions_list(), or all available versions and binaries with chrome_versions_list("all").

chrome_versions_list()
#> # A tibble: 2 × 6
#>   version       revision binary                platform  url                        path 
#>   <chr>         <chr>    <chr>                 <chr>     <chr>                      <chr>
#> 1 134.0.6998.88 1415337  chrome                mac-arm64 https://storage.googleapi… /Use…
#> 2 134.0.6998.88 1415337  chrome-headless-shell mac-arm64 https://storage.googleapi… /Use…

Technincal Note: chrome-headless-shell

chromote runs Chrome in "headless mode", i.e. without a visual interface. Between versions 120 and 132 of Chrome, there were, essentially, two flavors of headless mode.

chrome-headless-shell is the version of Chrome's headless mode that is designed and best suited for automated testing, screenshots and printing, typically referred to as "old headless" mode.

In most uses of chromote, chrome-headless-shell is an appropriate choice. It will generally load faster and run more quickly than the alternative headless mode which uses the same version of Chrome you use when browsing, but without the UI. After v132, old headless mode is no longer included in the Chrome binary, but the chrome-headless-shell binary is available from v120+.

local_chrome_version() sets the version of Chrome for the current session or within the context of a function. For small tasks where you want to use a specific version of Chrome for a few lines of code, chromote provides a with_chrome_version() variant:

with_chrome_version("132", {
  # Take a screenshot with Chrome v132
  webshot2::webshot("https://r-project.org")
})

Finally, you can manage Chrome binaries directly with three helper functions:

chrome_versions_add() can be used to add a new Chrome version to the cache, without explicitly configuring chromote to use that version.
chrome_versions_path() returns the path to the Chrome binary for a given version and binary type.
chrome_versions_remove() can be used to delete copies of Chrome from the local cache.

Note for Windows users

Chrome for Windows includes a setup.exe file that chromote runs when it extracts the Chrome zipfile. This file is provided by Chrome and is used to set the correct permissions on the chrome.exe executable file. Sometimes, running setup.exe returns an error, even if it works correctly.

If you do encounter errors using a downloaded version of Chrome, use chrome_versions_path() to get the path to the problematic executable. Then, try running this executable yourself with the Run command (from the Start menu). This typically resolves any lingering permissions issues.

Using a Chrome-based browser that you installed

Chromote will look in specific places for the Chrome web browser, depending on platform. This is done by the chromote:::find_chrome() function.

If you wish to use a different browser from the default, you can set the CHROMOTE_CHROME environment variable, either with Sys.setenv(CHROMOTE_CHROME="/path/to/browser").

library(chromote)
Sys.setenv(CHROMOTE_CHROME = "/Applications/Chromium.app/Contents/MacOS/Chromium")

b <- ChromoteSession$new()
b$view()
b$Page$navigate("https://www.whatismybrowser.com/")

Another way is create a Chromote object and explicitly specify the browser, then spawn ChromoteSessions from it.

m <- Chromote$new(
  browser = Chrome$new(path = "/Applications/Chromium.app/Contents/MacOS/Chromium")
)

# Spawn a ChromoteSession from the Chromote object
b <- m$new_session()
b$Page$navigate("https://www.whatismybrowser.com/")

Yet another way is to create a Chromote object with a specified browser, then set it as the default Chromote object.

m <- Chromote$new(
  browser = Chrome$new(path = "/Applications/Chromium.app/Contents/MacOS/Chromium")
)

# Set this Chromote object as the default. Then any
# ChromoteSession$new() will be spawned from it.
set_default_chromote_object(m)
b <- ChromoteSession$new()
b$view()
b$Page$navigate("https://www.whatismybrowser.com/")