JavaScript has already managed to become one of the most popular languages that are used for web scraping. It is quite user-friendly, which is impossible not to mention. Also, the ability to get all the necessary data from SPA significantly increases its popularity among all specialists in this niche.
In turn, Node.JS is the JavaScript execution environment itself. It is on this server that you can and apply the language to its fullest extent. Thus, web scraping on javascript and web scraping on node js is characterized by the process of extracting information from selected websites using these two necessary components that were outlined earlier. It is necessary to understand the principles of the process in more detail and know what is web scraping?
What is web scraping?
Web scraping is represented as the process of obtaining information from some sites for other sites by so-called “raw” HTML requests on other servers. This happens thanks to HTTP requests. After mining certain data, the system processes it, and brings it into the desired format. It is worth noting that there are quite a few known areas of application of such a technique. For example:
- SEO;
- lead generation;
- news tracking;
- price analysis.
In search engine optimization, web scraping is needed for detailed analysis of search engine results. This is used for finding and creating additional keywords or working out on developing a site filled with content. Also web scraping is very useful if the user is a person to get access to much more news around the world, regardless of his real location. The technique makes it possible to automatically get the contact information of a person who is a potential possible customer. This is very useful in the work of online stores or other platforms that sell a particular product or service. Web scraping helps to quickly get information about prices in certain stores. It greatly simplifies the process of “manual” search. Thus, this principle is applied in quite a few niches.
But web scraping is also applied when the chosen platforms do not provide APIs to get the necessary data. You may ask: why do we need web scraping if all commercial sites provide a working API?
Yes, indeed – commercial servers give access to an API. But it can’t always provide all the information you need. It is to get a “report” of everything that web scraping can be applied.
Web scraping with JavaScript
But how to parse websites with javascript and node.js? Usually, web scraping with JavaScript can be chosen for several reasons at once. First, a lot of platforms nowadays use exactly dynamic content. Here, JavaScript has the advantage of being able to accept and handle it properly.
On pages where you need to interact with interactive elements, it is JavaScript that will show all its functionality. Also, some sites may plug in special protection to avoid web scraping. In this case, JavaScript is known for its ability to masterfully bypass any obstacles. It will ensure that the maximum amount of data is displayed with little loading time. Thus, it can be seen that JavaScript is one of the most sought after ways of conducting web scraping. What is interesting is that fast mobile proxies will help ensure more efficient online activities – for those people who work in this niche, such an opportunity will be very promising.
Pre-requisites
What is important to note is that there are a few basic requirements. You need to know them before you implement web scraping with node.js and Node.JS. Initially, you should definitely make sure that Node.JS is installed on your device. You can download this program through the official website. There are certain packages without which web scraping is impossible. For example, axios and cheerio can be freely used to perform HTTP requests and work with HTML. You can install these items by entering a specific request on the command line. These packages will become very useful while executing requests, downloading and analyzing the received data. One should not forget the importance of knowing the basics of JavaScript. This is a key point for successful work. After all, without certain knowledge and skills, you will not be able to work with massive objects, loops and conditional operators. It should be said that web scraping very often may require the implementation of asynchronous programming. You should make sure that you can understand it and be able to reproduce it in JavaScript. A person should be well versed with the basics of HTML and CSS. This is needed because of the fact that the process of web scraping involves interacting with specific elements on the page. Because of this, the user must know all aspects of their organization in an HTML document. It is also no secret that understanding the most basic concepts of networking and the HTTP protocol is simply necessary for sending requests and processing responses from a particular site. Keep in mind that some sites have specific rules in place. They are the ones that prohibit the use of web scraping in certain service environments. You need to make sure that you will not violate possible rules and ethical standards. As you can understand, all these aspects are extremely important to conduct a successful scraping process. Of course, a person without in-depth programming knowledge will most likely simply not be able to carry out such complex operations.
JavaScript libraries for web scraping using Node.js
There are special libraries that help to conduct web scraping with javascript. Specialists and users highlight a few of the best ones that exist:
- Axios;
- SuperAgent;
- Unirest;
- Puppeteer;
- Nightmare;
- Playwright.
It is necessary to familiarize in detail with all the strengths and weaknesses of each library. But first, it is worth considering a concept that is often encountered – HTTP client. These HTTP clients are used to interact with the site. To be more specific, it is used to send requests and receive responses.
Axios
Axios is a kind of HTTP client that is designed with the basic characteristics of washes for Node.js or any other browsers. Axios is popular among all developers due to its quite simple methods and quality maintenance. Also, this library perfectly supports certain chips. For example, with it you can cancel requests, enable automatic transformation of JSON data. Installation of the library is possible only using the npm i axios command. Users note a few of the most important advantages. For example, the library has the ability to intercept an HTTP request. It is very well-known among many users. This is what makes it so reliable. On a programming love server, if the topic is specifically about web scraping, you can hear constant discussions about this library. It easily converts request and response data in the shortest possible time.
SuperAgent
SuperAgent acts as another popular library for any browser and platform. What sets it apart is that it can support a wide variety of high-level HTTP client chips – an advantage for many. This library will be able to work with promis or async/await syntax. Installation is possible with the npm i superagent command. SuperAgent can be easily extended by using various plugins. It will work well in any browser or node. But it has its own drawbacks. Yes, users have long noticed that it has a much smaller number of supported features, if compared to other libraries. There is also a question regarding its documentation. After all, it is not presented in enough detail, which alarms some users of the library.
Unirest
Unirest is a special library that is created and supported by Kong. It provides several of the most popular languages at once. You can familiarize yourself with a wide variety of methods, such as DELETE, POST, GET, HEAD. All of them are easy to add to applications. It is because of this that the library can be used even for simple usecases. Unirest also impresses with its speed. Yes, it can support any commands, execute them in a short time and not overload after active use. Transferring files from servers is as simple as possible.
Puppeteer
Puppeteer is developed by the Google system. The library has a high-level API. It makes it possible to manage Chrome or Chromium. It can deal with the generation of PDF files and websites. It is possible to apply it to those pages that also use JavaScript if there is dynamic loading information.
Nightmare
Nightmare is a high-level library that helps to perform browser automation or web scraping. It uses a special framework – Electron – for its operation. It is this framework that makes it possible to access the headless-browser. It is worth noting that it makes the work much easier. The main advantage of this library is that it will require much less resources to work. But you can also notice certain disadvantages. For example, the library does not have normal support from the creators. Electron has certain problems that are noticeable only after you start using it.
Playwright
Playwright provides automation for search engines like Firefox, Safari, Chrome. This library was created by the same team that developed Puppeteer. The system provides functioning in a special headless or non-headless mode. This significantly affects the entire optimization of the tasks. The advantage is that the library supports a lot of functions. The system also supports several languages, including Javascript. Users note the fact that it works much faster than any other library. All the documentation is written well enough, which makes it easy for users to learn. Each user can independently choose any library that will be maximally suitable for his needs.
A practical guide to web scraping in Node.JS
You need to know that there are a few basic steps that will help you conduct web scraping efficiently.
Step 1: Customizing the Node.js environment. The first step is to set up the development environment itself. There are several ways to set up the labor-intensive required module. But the most comfortable for many people has already become the use of the npm node package manager. You can also simply download a ready-made GitHub module. Node.js uses a quality TDS protocol – it is part of SQL Server and the SQL Azure database. No additional customizations are required after that.
Step 2: Create a new Node.js project. The first thing to do is to create a new directory on the command line. To initialize the project, you need to enter the npm init command. To create the project, you need to develop a new file – it will contain the project code. Then you can start writing the code of the application itself. As a test, you should try to launch the application.
Step 3: Install Axios and Cheerio. You need to download the two main packages that many users use to do their work. In our case, these are Axios for sending HTTP requests and Cheerio for parsing HTML.
Step 4: Study the HTML page. We also need to study in detail the HTML page we will be working with later. To do this, you need to open the landing page and find its HTML code. After that, you should study it in detail.
Step 5: Select HTML elements using Cheerio. You can apply Cheerio to select and manipulate HTML elements. This is accomplished through the use of jQuery-like syntax. There are several examples of how to select elements using Cheerio:
- selecting elements by tag;
- by class;
- by identifier;
- by attribute;
- using combinators.
It is Cheerio that makes it possible to use many other methods and functions, such as each, text, html, and more, for more sophisticated data manipulation.
Step 6: Retrieving data from the landing page. The next step is to retrieve data from the landing page. You can use fetching text from an element, attribute, integration by selected elements. Each method requires different code.
Step 7: Selecting and extracting data. Data extraction is done depending on what we want to extract. For example, if we are tracking news and want to extract headlines, in this case we need to enter a function to retrieve the page code. Next, we should lead the function with what we want to extract. In our case it is headlines – async function extractNewsHeadlines(url) {. After that, we need to load the HTML into Cheerio. Then we need to select and extract specific headlines or any other data. At the end the extracted data needs to be processed.
Step 8: Pagination and working with it. If you need to retrieve data from multiple pages, implement pagination. To do this, apply a loop or recursive calls to handle multiple pages.
Step 9: Storing the extracted data. You need to decide how you want to store the extracted data. You can save it immediately to a file, database or use it as you wish.
Step 10: Launch the web scraper. To launch, you must create an entry point to the web scraper and launch it. The web scraper can be started by calling the main function you have already created.
Conclusion
Thus, we have dealt with the basic aspects of web scraping and its wide range of applications. Web scraping is a technique has many advantages that are worth knowing. Web scraping is a highly complex process that requires utmost care and already acquired programming skills.