Tools to Scrape Dynamic Web Content via the ‘HtmlUnit’ Java Library
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README.md

Signedby Linux buildStatus CoverageStatus Minimal RVersion License

htmlunit

Tools to Scrape Dynamic Web Content via the ‘HtmlUnit’ Java Library

Description

‘HtmlUnit’ (https://htmlunit.sourceforge.net/) is a “‘GUI’-Less browser for ‘Java’ programs”. It models ‘HTML’ documents and provides an ‘API’ that allows one to invoke pages, fill out forms, click links and more just like one does in a “normal” browser. The library has fairly good and constantly improving ‘JavaScript’ support and is able to work even with quite complex ‘AJAX’ libraries, simulating ‘Chrome’, ‘Firefox’ or ‘Internet Explorer’ depending on the configuration used. It is typically used for testing purposes or to retrieve information from web sites. Tools are provided to work with this library at a higher level than provided by the exposed ‘Java’ libraries in the ‘htmlunitjars’ package.

What’s Inside The Tin

The following functions are implemented:

DSL

  • web_client/webclient: Create a new HtmlUnit WebClient instance

  • wc_go: Visit a URL

  • wc_html_nodes: Select nodes from web client active page html content

  • wc_html_text: Extract attributes, text and tag name from webclient page html content

  • wc_html_attr: Extract attributes, text and tag name from webclient page html content

  • wc_html_name: Extract attributes, text and tag name from webclient page html content

  • wc_headers: Return response headers of the last web request for current page

  • wc_browser_info: Retreive information about the browser used to create the ‘webclient’

  • wc_content_length: Return content length of the last web request for current page

  • wc_content_type: Return content type of web request for current page

  • wc_render: Retrieve current page contents

  • wc_css: Enable/Disable CSS support

  • wc_dnt: Enable/Disable Do-Not-Track

  • wc_geo: Enable/Disable Geolocation

  • wc_img_dl: Enable/Disable Image Downloading

  • wc_load_time: Return load time of the last web request for current page

  • wc_resize: Resize the virtual browser window

  • wc_status: Return status code of web request for current page

  • wc_timeout: Change default request timeout

  • wc_title: Return page title for current page

  • wc_url: Return load time of the last web request for current page

  • wc_use_insecure_ssl: Enable/Disable Ignoring SSL Validation Issues

  • wc_wait: Block HtlUnit final rendering blocks until all background JavaScript tasks have finished executing

Just the Content (pls)

  • hu_read_html: Read HTML from a URL with Browser Emulation & in a JavaScript Context

Content++

  • wc_inspect: Perform a “Developer Tools”-like Network Inspection of a URL

Installation

install.packages("htmlunit", repos = c("https://cinc.rud.is", "https://cloud.r-project.org/"))
# or
remotes::install_git("https://git.rud.is/hrbrmstr/htmlunit.git")
# or
remotes::install_git("https://git.sr.ht/~hrbrmstr/htmlunit")
# or
remotes::install_gitlab("hrbrmstr/htmlunit")
# or
remotes::install_bitbucket("hrbrmstr/htmlunit")
# or
remotes::install_github("hrbrmstr/htmlunit")

NOTE: To use the ‘remotes’ install options you will need to have the {remotes} package installed.

Usage

library(htmlunit)
library(tidyverse) # for some data ops; not req'd for pkg

# current verison
packageVersion("htmlunit")
## [1] '0.4.0'

Something xml2::read_html() cannot do, read the table from https://hrbrmstr.github.io/htmlunitjars/index.html:

test_url <- "https://hrbrmstr.github.io/htmlunitjars/index.html"

pg <- xml2::read_html(test_url)

html_table(pg)
## list()

☹️

But, hu_read_html() can!

pg <- hu_read_html(test_url)

html_table(pg)
## [[1]]
##      X1   X2
## 1   One  Two
## 2 Three Four
## 3  Five  Six

All without needing a separate Selenium or Splash server instance.

Content++

We can also get a HAR-like content + metadata dump:

xdf <- wc_inspect("https://rstudio.com")

colnames(xdf)
## [1] "method"         "url"            "status_code"    "message"        "content"        "content_length"
## [7] "content_type"   "load_time"      "headers"

select(xdf, method, url, status_code, content_length, load_time)
## # A tibble: 59 x 5
##    method url                                                                       status_code content_length load_time
##    <chr>  <chr>                                                                           <int>          <dbl>     <dbl>
##  1 GET    https://rstudio.com/                                                              200          13531       625
##  2 GET    https://use.fontawesome.com/releases/v5.0.6/css/all.css                           200           8699       376
##  3 GET    https://d33wubrfki0l68.cloudfront.net/bundles/c5ddb3e999592179708beea702…         200          53046       563
##  4 GET    https://cdn.rawgit.com/noelboss/featherlight/1.7.13/release/featherlight…         200            763       376
##  5 GET    https://d33wubrfki0l68.cloudfront.net/css/4a0f49009a213e6e2207c6f66893f0…         200            505        73
##  6 GET    https://gitcdn.github.io/bootstrap-toggle/2.2.2/css/bootstrap-toggle.min…         200            548       258
##  7 GET    https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-aweso…         200           6663       247
##  8 GET    https://metadata-static-files.sfo2.cdn.digitaloceanspaces.com/pixel/lp.js         200           3876       364
##  9 GET    https://snap.licdn.com/li.lms-analytics/insight.min.js                            200           1576       455
## 10 GET    https://connect.facebook.net/en_US/fbevents.js                                    200          31766       412
## # … with 49 more rows

group_by(xdf, content_type) %>% 
  summarise(
    total_size = sum(content_length), 
    total_load_time = sum(load_time)/1000
  )
## # A tibble: 12 x 3
##    content_type               total_size total_load_time
##    <chr>                           <dbl>           <dbl>
##  1 ""                                  0           1.02 
##  2 "application/javascript"       443531           3.61 
##  3 "application/json"               4176           3.10 
##  4 "application/x-javascript"     161004           1.69 
##  5 "image/gif"                       131           0.561
##  6 "image/jpeg"                    59772           0.105
##  7 "image/png"                     40634           0.234
##  8 "image/svg+xml"                 10869           0.303
##  9 "text/css"                     121175           2.81 
## 10 "text/html"                     14425           1.3  
## 11 "text/javascript"              174172           1.42 
## 12 "text/plain"                       28           0.354

DSL

wc <- web_client(emulate = "chrome")

wc %>% wc_browser_info()
## < Netscape / 5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.122 Safari/537.36 / en-US >

wc <- web_client()

wc %>% wc_go("https://usa.gov/")

# if you want to use purrr::map_ functions the result of wc_html_nodes() needs to be passed to as.list()

wc %>%
  wc_html_nodes("a") %>%
  sapply(wc_html_text, trim = TRUE) %>% 
  head(10)
##  [1] "Skip to main content"               ""                                   "Español"                           
##  [4] "1-844-USA-GOV1"                     "All Topics and Services"            "About the U.S."                    
##  [7] "American Flag"                      "Branches of the U.S. Government"    "Budget of the U.S. Government"     
## [10] "Data and Statistics about the U.S."

wc %>%
  wc_html_nodes(xpath=".//a") %>%
  sapply(wc_html_text, trim = TRUE) %>% 
  head(10)
##  [1] "Skip to main content"               ""                                   "Español"                           
##  [4] "1-844-USA-GOV1"                     "All Topics and Services"            "About the U.S."                    
##  [7] "American Flag"                      "Branches of the U.S. Government"    "Budget of the U.S. Government"     
## [10] "Data and Statistics about the U.S."

wc %>%
  wc_html_nodes(xpath=".//a") %>%
  sapply(wc_html_attr, "href") %>% 
  head(10)
##  [1] "#content"                "/"                       "/espanol/"               "/phone"                 
##  [5] "/#tpcs"                  "#"                       "/flag"                   "/branches-of-government"
##  [9] "/budget"                 "/statistics"

Handy function to get rendered plain text for text mining:

wc %>% 
  wc_render("text") %>% 
  substr(1, 300) %>% 
  cat()
## Official Guide to Government Information and Services | USAGov
## Skip to main content
## An official website of the United States government Here's how you know
## 
## 
## Search
## Search
## Search
## 1-844-USA-GOV1
## All Topics and Services
## Benefits, Grants, Loans
## Government Agencies and Elected Officials
## Jobs and Unemplo

htmlunit Metrics

Lang # Files (%) LoC (%) Blank lines (%) # Lines (%)
R 13 0.76 320 0.75 182 0.73 372 0.83
Rmd 1 0.06 41 0.10 52 0.21 75 0.17
Maven 1 0.06 30 0.07 0 0.00 1 0.00
Java 1 0.06 28 0.07 12 0.05 0 0.00
make 1 0.06 10 0.02 4 0.02 0 0.00

Code of Conduct

Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms.