Book Image

Go Web Scraping Quick Start Guide

By : Vincent Smith
Book Image

Go Web Scraping Quick Start Guide

By: Vincent Smith

Overview of this book

Web scraping is the process of extracting information from the web using various tools that perform scraping and crawling. Go is emerging as the language of choice for scraping using a variety of libraries. This book will quickly explain to you, how to scrape data data from various websites using Go libraries such as Colly and Goquery. The book starts with an introduction to the use cases of building a web scraper and the main features of the Go programming language, along with setting up a Go environment. It then moves on to HTTP requests and responses and talks about how Go handles them. You will also learn about a number of basic web scraping etiquettes. You will be taught how to navigate through a website, using a breadth-first and then a depth-first search, as well as find and follow links. You will get to know about the ways to track history in order to avoid loops and to protect your web scraper using proxies. Finally the book will cover the Go concurrency model, and how to run scrapers in parallel, along with large-scale distributed web scraping.
Table of Contents (10 chapters)

Searching using the regexp package

The regexp package in the Go standard library provides a deeper level of search by using regular expressions. This defines a syntax that allows you to search for strings in more complex terms, as well as retrieving strings from a document. By using capture groups in regular expressions, you can extract data matching a query from the web page. Here are a few useful tasks that the regexp package can help you achieve.

Example – Finding links

In the previous section, we used the strings package to count the number of links on a page. By using the regexp package, we can take this example further and retrieve the actual links with the following regular expression:

 <a.*href\s*=\s*[...