goqueryvschompjs
goquery brings a syntax and a set of features similar to jQuery to the Go language. goquery is a popular and easy-to-use library for Go that allows you to use a CSS selector-like syntax to select elements from an HTML document.
It is based on Go's net/html package and the CSS Selector library cascadia. Since the net/html parser returns nodes, and not a full-featured DOM tree, jQuery's stateful manipulation functions (like height(), css(), detach()) have been left off.
Also, because the net/html parser requires UTF-8 encoding, so does goquery: it is the caller's responsibility to ensure that the source document provides UTF-8 encoded HTML. See the wiki for various options to do this. Syntax-wise, it is as close as possible to jQuery, with the same function names when possible, and that warm and fuzzy chainable interface. jQuery being the ultra-popular library that it is, I felt that writing a similar HTML-manipulating library was better to follow its API than to start anew (in the same spirit as Go's fmt package), even though some of its methods are less than intuitive (looking at you, index()...).
goquery can download HTML by itself (using built-in http client) though it's not recommended for web scraping as it's likely to be blocked.
chompjs can be used in web scrapping for turning JavaScript objects embedded in pages into valid Python dictionaries.
In web scraping this is particularly useful for parsing Javascript variables like:
import chompjs
js = """
var myObj = {
myMethod: function(params) {
// ...
},
myValue: 100
}
"""
chompjs.parse_js_object(js, json_params={'strict': False})
{'myMethod': 'function(params) {\n // ...\n }', 'myValue': 100}
In practice this can be used to extract hidden JSON data like data from <script id=__NEXT_DATA__> elements
from nextjs (and similar) websites. Unlike json.loads command chompjs can ingest json documents that contain
javascript natives like functions making it a super easy way to scrape hidden web data objects.
Example Use
package main
import (
"fmt"
"github.com/PuerkitoBio/goquery"
)
func main() {
// Use goquery.NewDocument to load an HTML document
// This can load from URL
doc, err := goquery.NewDocument("http://example.com")
// or HTML string:
doc, err := goquery.NewDocumentFromReader("some html")
if err != nil {
fmt.Println("Error:", err)
return
}
// Use the Selection.Find method to select elements from the document
doc.Find("a").Each(func(i int, s *goquery.Selection) {
// Use the Selection.Text method to get the text of the element
fmt.Println(s.Text())
// Use the Selection.Attr method to get the value of an attribute
fmt.Println(s.Attr("href"))
})
}
# basic use
import chompjs
js = """
var myObj = {
myMethod: function(params) {
// ...
},
myValue: 100
}
"""
chompjs.parse_js_object(js, json_params={'strict': False})
{'myMethod': 'function(params) {\n // ...\n }', 'myValue': 100}
# example how to use with hidden data parsing:
import httpx
import chompjs
from parsel import Selector
response = httpx.get("http://example.com")
hidden_script = Selector(response.text).css("script#__NEXT_DATA__::text").get()
data = chompjs.parse_js_object(hidden_script)
print(data['props'])