--- title: "selenider and rvest" output: rmarkdown::html_vignette vignette: > %\VignetteIndexEntry{selenider and rvest} %\VignetteEngine{knitr::rmarkdown} %\VignetteEncoding{UTF-8} --- ```{r, include = FALSE} available <- selenider::selenider_available() knitr::opts_chunk$set( collapse = TRUE, comment = "#>", eval = available ) ``` ```{r, eval = !available, include = FALSE} message("Selenider is not available") ``` selenider can be a useful add-on to rvest, for when scraping data requires interaction with a website. rvest is very similar to selenider, but is designed for static webpages rather than interactive ones. ```{r setup} library(rvest) library(selenider) ``` To start, let's open ```{r} open_url("https://www.r-project.org/") ``` First, we will interact with the website with selenider. We would like to find the most recent post by R on Mastodon, and follow the link to the original post. ```{r} s(".mt-timeline") |> find_element("article") |> elem_attr("data-location") |> open_url() ``` Now, we would like to parse the text of the post using `rvest::html_text2()`. We can do this in two ways, either by locating the element containing the post using selenider then parsing it using rvest, or by parsing the entire page using rvest and finding the element after. The two methods are very similar, since selenider and rvest use a very similar syntax, except rvest uses the `html_` prefix rather than the `elem_` prefix. We can convert between selenider elements and rvest (or more precisely, xml2) documents using `rvest::read_html()` or `xml2::read_html()`. Note that when converting elements to rvest nodes, the element will be wrapped in a `` tag. ```{r} # First method rvest_element <- s(".columns-area") |> find_element(".status__content") |> read_html() rvest_element html_text2(rvest_element) ``` Reading the HTML of an entire page can be done using `get_page_source()`. Note that `rvest::html_element()` is equivalent to `find_element()`, but works only on static HTML. ```{r} get_page_source() |> html_element(".columns-area") |> html_element(".status__content") |> html_text2() ```