Posted on: 26th Oct 2023 223 Views

Learn How to Build a Web Scraper With Node.JS

Collecting data from the web is increasingly becoming a necessity in various industries, especially in businesses, where the value of information cannot be understated, hence the essence of web scraping.

So what exactly is web scraping? Simply put, it is the process of obtaining information automatically from the internet on a larger scale. It comes in handy for research, analysis, and automation.

The scraped data is usually unstructured and in an HTML format, but it is converted into structured data in a spreadsheet or a database form. This is why all efforts must be made to ensure that web scraping is easier and more effective, and in comes Node.js.

If you are looking to learn to build a web scraper using Node.js, this guide will walk you through the entire process. Come along!

Building a Web  Scraper With Node.js

Node.js is a lightweight, efficient, and high-performance platform widely preferred for its ability to handle multiple web scraping requests running simultaneously. It is also cross-platform, so if you’re looking for a versatile choice for your web scraping projects, you may have just hit gold.

With a large community creating and providing support for web scraping libraries, Node.js comes with all the necessary tools and support to ensure that all your web scraping needs are met. But how can we use it to build a web scraper? Here’s how.

Step 1: Check for Restrictions and Permissions

Before scraping a website, it’s always crucial to read the terms of use and ensure that there are no restrictions or permissions required for web scraping or its frequency on the website. The same applies when building a web scraper using Node.js.

Step 2: Create the Project

Start by creating a new folder in your Windows Explorer and giving it a memorable name. Then you’ll need to add the necessary files to your project, but first ensure that Node.js is installed and open up the folder in VScode, at which point it should be empty.

After installing Node.js, use the Node Package Manager, open the terminal in VScode, and run:

cd Custom Web Scraper

After being redirected to the current project directory, enter:

npm init

You will need to store all packages in one file, and this command initialises a project while creating a package.json file for that purpose. You will then receive some prompts about the information that you want to store in the file, and you need to note the created entry, index.js. Open up the package.json file contained in your project, and this is how the fields will look:

{

 “name”: “custom-web-scraper”,

 “version”: “1.0.0”,

 “description”: “”,

 “main”: “index.js”,

 “scripts”: {

   “test”: “”

 },

 “author”: “”,

 “license”: “ISC”

}

With the entry point as index.js in the package.json file, you’ll need to create a new file where your code will be written and name it index.js.

Step 3: Installing the Necessary Packages

Node.js has a host of options for web scraping. These include Cheerio, Puppeter, and Axio, which all have a role to play in building a web scraper. Here’s how to install them.

  • Install Cheerio

Cheerio is a great tool if you want to traverse a web page without much fuss. It is also used to parse markup and pick up HTML elements from a webpage, not to mention providing you with an API to edit and manipulate the data structure. To install the Cheerio dependency in the package.json you created, run:

npm i cheerio

  • Install Axios

Axios works hand in hand with Cheerio by making HTTP requests, which is an essential part of the web scraping process. To install the dependency, run the command:

npm i Axios

  • Install Puppeteer

When it comes to test automation, no Node.js library is as effective as Puppeteer. This is because it offers a high-level API to facilitate the automation of most tasks in the Chrome browser through the DevTools protocol. To install it, run:

npm i puppeteer

By working as a headless browser, Puppeteer avails itself as one of the best options for scraping dynamic AJAX pages or data in JS elements. And although it requires much longer code than other Node.js scraping libraries, the process of using it is simple and clear.

Step 4: Set Up Your Project Directory

For the new project, you will need to create a new directory to avoid any mix-ups with other projects. To create a new directory and file, use this command:

mkdir my-web-scraper

cd my-web-scraper

touch scraper.js

Step 5: Making HTTP Requests

When scraping the web, one of the most important steps is making HTTPS requests. Luckily, with Node.js, it has an in-built HTTP module, making the process even easier and more effective. On the other hand, you can always use Axios to make the request.

To make HTTPS requests with Node.js, run this command:

const http = require(‘http’);

const url = ‘http://example.com’;

http.get(url, (res) => {

let data = ”; res.on(‘data’, (chunk) => { data += chunk; });

res.on(‘end’, () => {

console.log(data);

});

});

You can replace http://example.com with the URL of the website that you aim to scrape.

Step 6: Scraping HTML

Once you have obtained the HTML content of a page, it’s time to extract the data that you need by parsing it. For this, there are several third-party libraries for support, including Cheerio and JSDOM. Since we already installed Cheerio, how does it work for scraping HTML with Node.js?

To parse HTML and extract data, here is an example code:

const cheerio = require(‘cheerio’);

const request = require(‘request’);

const url = ‘https://example.com’;

request(url, (error, response, html) => {

if (!error && response.statusCode == 200) {

const $ = cheerio.load(html);

const title = $(‘title’).text();

const firstParagraph = $(‘p’).first().text();

console.log(title); console.log(firstParagraph);

}

});

The code will use the request library to collect and present the HTML content. For this particular code, this is where Cheerio comes in to parse the text and extract the title and first paragraph. Otherwise, the command can be edited to collect the required set of data from the source.

Web Scraping with Node.js Best Practises

  • Always limit the number of requests you make with the scraper to avoid overloading the website.
  • Adjust the headers, rate limiting, and other settings of the scraper after monitoring it closely to ensure it is working effectively.
  • The scraper would be more effective if you cached extracted data and webpages, as it reduces the load on the website.
  • Double-check to ensure that the webpage you are scraping doesn’t have restrictions on the frequency of scraping.

And there you go! In this article, we have explored the process of setting up and scraping the web using Node.js. Whether you intend to use it in business or to get help with assignments, this knowledge will prove invaluable.

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