node-fetchvsrvest
node-fetch is a lightweight library that provides a fetch()-like API for making HTTP requests in Node.js. It is a light-weight implementation of the Fetch API, which is mostly compatible with the browser's version.
node-fetch is primarily known as almost identical package fetch() is included in web browsers so it shares the same use common API. It's great starting point for people coming from front-end environment.
rvest is a popular R library for web scraping and parsing HTML and XML documents. It is built on top of the xml2 and httr libraries and provides a simple and consistent API for interacting with web pages.
One of the main advantages of using rvest is its simplicity and ease of use. It provides a number of functions that make it easy to extract information from web pages, even for those who are not familiar with web scraping. The html_nodes and html_node functions allow you to select elements from an HTML document using CSS selectors, similar to how you would select elements in JavaScript.
rvest also provides functions for interacting with forms, including html_form, set_values, and submit_form functions. These functions make it easy to navigate through forms and submit data to the server, which can be useful when scraping sites that require authentication or when interacting with dynamic web pages.
rvest also provides functions for parsing XML documents. It includes xml_nodes and xml_node functions, which also use CSS selectors to select elements from an XML document, as well as xml_attrs and xml_attr functions to extract attributes from elements.
Another advantage of rvest is that it provides a way to handle cookies, so you can keep the session alive while scraping a website, and also you can handle redirections with handle_redirects
Highlights
Example Use
const fetch = require('node-fetch');
// fetch supports both Promises and async/await
fetch('http://httpbin.org/get')
.then(res => res.text())
.then(body => console.log(body))
.catch(err => console.error(err));
const response = await fetch('http://httpbin.org/get');
// for concurrent scraping Promise.all can be used
const results = await Promise.all([
fetch('http://httpbin.org/html'),
fetch('http://httpbin.org/html'),
fetch('http://httpbin.org/html'),
])
// POST requests
await fetch('http://httpbin.org/post', {
method: 'POST',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify({ name: 'John Doe' }),
})
// Proxy use:
const agent = new https.Agent({
rejectUnauthorized: false,
proxy: {
host: 'proxy.example.com',
port: 8080
}
});
await fetch('https://httpbin.org/ip', { agent })
// setting headers and cookies
const headers = new fetch.Headers();
headers.append('Cookie', 'myCookie=123');
headers.append('X-My-Header', 'myValue');
await fetch('https://httpbin.org/headers', { headers })
library("rvest")
# Rvest can use basic HTTP client to download remote HTML:
tree <- read_html("http://webscraping.fyi/lib/r/rvest")
# or read from string:
tree <- read_html('
<div class="products">
<a href="/product/1">Cat Food</a>
<a href="/product/2">Dog Food</a>
</div>
')
# to parse HTML trees with rvest we use r pipes (the %>% symbol) and html_element function:
# we can use css selectors:
print(tree %>% html_element(".products>a") %>% html_text())
# "[1] "\nCat Food\nDog Food\n""
# or XPath:
print(tree %>% html_element(xpath="//div[@class='products']/a") %>% html_text())
# "[1] "\nCat Food\nDog Food\n""
# Additionally rvest offers many quality of life functions:
# html_text2 - removes trailing and leading spaces and joins values
print(tree %>% html_element("div") %>% html_text2())
# "[1] "Cat Food Dog Food""
# html_attr - selects element's attribute:
print(tree %>% html_element("div") %>% html_attr('class'))
# "products"