What is HTML Parsing?
If you are asking, “What is HTML parser?” you may be considering the process of web scraping and using data from the web to answer questions you have. An HTML parser is a type of tool, or more accurately, a piece of software, that is used to read and interpret HTML code. When you learn how to parse HTML, you can automate the process of capturing data online and interpreting what it says, giving you the ability to make decisions for your company, enhance your research, or gather data for another need.
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In this tool, we will discuss what an HTML parser is in the sense of how to use it for data extraction. You will learn more about how it works and what you can do to analyze, manipulate, and extract data using an HTML parser. We also have a few recommendations of tools and steps to use to make the entire process easy for you to manage.
HTML Parsing: What It Is
So, what is an HTML parser to start with? The term “parsing” refers to the process of dividing something into components based on their syntactic roles. HTML parsing is a way to read and interpret HTML code so that all of that detailed code can provide you with just the information you need. We use an HTML parser to do this work. It will analyze, manipulate, or extract the data from web pages. By following this process, we take raw HTML text and break it down into a structured format. This then allows for our web scraper or other tools to find elements valuable to our search, such as tags, attributes, or text content.
With web scraping, our goal is to extract data from web pages and to automate as much of that process as possible. HTML parsing makes that possible. HTML parsers are essential for web scraping, browser rendering, and validating web content.
How to Parse HTML with Python
Our recommendation is to consider Python. What is HTML parsing in Python? By using Python for HTML parsing, you benefit from a variety of the benefits that make this computer language so popular. Python is simple to use, highly readable in itself, and has a huge selection of libraries that can make the entire process, including handling HTML, more streamlined and efficient.
If you plan to engage in parsing data from HTML using Python, which is excellent for most projects, including large-scale web scraping, then you’ll likely use the BeautifulSoup library to help you with parsing data from HTML. If you plan to go that route, our guide on web scraping in Python with BeautifulSoup breaks down the process for you, making the entire process easy and even efficient to do. Parsing with BeautifulSoup allows you to take advantage of key features, including locating elements with simple tags, class and ID selection, and extracting attributes. HTML parsing methods in BeautifulSoup include:
- Tags and elements: You can parse data by specific HTML tags, such as <p> for paragraphs or <a> for links. This helps when you are targeting general content structures.
- Class and ID Searching: For complex web pages, elements are often organized by class or ID attributes. BeautifulSoup makes it easy to locate elements by their class name. This allows you to find the specific information quickly, including information hidden within divs or nested elements.
- Navigating HTML Trees: You can navigate through a webpage’s DOM (Document Object Model) to target nested elements and extract data.
Parsing data from HTML using Python and BeautifulSoup tends to be the ideal choice, but it is not the only option.
Parsing HTML with Java
For those who are using Java for web scraping, you may want the same type of flexibility and functionality as Python, and you really do get that in jsoup. It can work as an HTML parser for your project. That’s because jsoup is a Java library. It implements the WHATWG HTML5 specification. You can use it for parsing all HTML documents. It can find and extract data from complex HTML documents for you. And, you can use it to manipulate those HTML elements based on your project goals.
Have you read our tutorial, “The Ultimate Guide to Getting Started with Web Scraping with Java?” That’s a good place to start to learn a bit more about why Java works so well for these projects, if you have experience using it. Then, you can use jsoup as your tool for parsing HTML in that process. It is quite a simple product to learn to use and makes for an excellent component of your project.
For parsing HTML, jsoup is rather direct. It will parse the HTML of a webpage and then convert it into a Document object. This object is a programmatic representation of the DOM. To create this document, you will use the parse method with multiple overloads that allow you to accept various types of input.
For example, you may use the following:
parse(String html): parses an HTML string or parse(InputStream in, @Nullable String charsetName, String baseUri): reads an InputStream and then will parse it
This is what an HTML parser is supposed to do. It provides you with the information you need. Parsing in HTML with Java isn’t complex and should not be something you have to spend a lot of time learning.
What Is HTML Parsing Used For?
Now that you have an idea of what an HTML parser is, consider how to parse HTML – what is the point of doing so?
Parsing is an analysis and conversion method. It analyzes and then converts a program or set of data into an internal format that ultimately can be used later. The browser will parse HTML into a DOM tree. A Document Object Model, or DOM, tree is a hierarchical representation of an HTML or XML document. It has a root node, which is the document, and then a series of child nodes. Each of these child nodes is a representation of the elements, attributes, or text content within the document. If you consider the concept as a tree, each node of that tree has a parent node. The only exception to that is the root node. Each node in the tree can also have multiple child nodes, like branches stemming from it.
With HTMLParse, the process typically includes tokenization and tree construction. HTML tokens will include a start and end tag. They will also have attribute names and values assigned to them. When the document is built, parsing HTML is rather direct and even simplistic overall. It gets more challenging when that is not the structure expected. The HTML parser will parse tokenized input into the document. In doing so, it builds the document tree.
During the parsing HTML process, if the parser finds what is called a non-blocking resource, the browser will request those resources and then continue to browse. One of the most common examples of this is an image embedded into the code. The parsing of HTML can continue when a CSS file is found. However, there are some elements that will block the process, including rendering. That includes <script> tags—particularly those without an async or defer attribute. When this happens, it blocks rendering, and the parsing of HTML is paused.
Another potential part of the process is when the browser encounters CSS styles. When that happens, it parses the text into the CSS object model. This is a type of data structure that it uses for styling layouts and for painting. In this situation, the browser creates a render tree from both structures. This allows it to paint the content to the screen.
The parser can also handle JavaScript. In these situations, it will download the file, parse it, and then execute the steps within. This is done during compile time. It can also be done when the parser is invoked, often during a call to a method.
For developers who learn how to parse HTML, it has various uses. For example, it can help with:
- Searching for specific elements within the structure of the HTML code. This is often the data that you need or want to use to analyze later for a project.
- Modify the page structures, which can be done to alter the way a page looks and functions to fit a different need than is currently in place.
- Clean up malformed HTML—and in doing so, help ensure your system and site are operating the way you deserve them to.
When using these tools, you gain a lot of support throughout the web scraping process. Note that if you have a reliable HTML parser, it will ensure that even in situations where the code is messy or even in situations where the code is incomplete, it can still be interpreted accurately. That makes the code usable for whatever project you are using it for.
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There are various data formats that parsers can work with. As noted throughout this document, HTML is the most common option. It allows the parsers to extract data from the HTML content. You can use a parsing library, like BeautifulSoup, to do this work for you (which lets you access data in XML or HTML documents). You can also use regular expressions; the Regex library is a tool that will help you to do this.
Remember, too, that parsing HTML can be done using a wide range of languages. That includes scripting languages that create a command series and then are executed without compilation, such as those used in games and apps. You can also use parsing with interactive processing data languages, which are often done in larger data projects. You can use it for database languages and SQL as well.
Parsers can be helpful with HTTPS and Internet Protocols, modeling languages, and other tools. Because of how important the work is that they are doing, you should take a few extra steps to learn how to parse HTML properly and use the tools that you are most comfortable with for this process.
If you need a bit more help on the process, check out a few of our guides:
- What is Parsing in Python
- How to Parse Data: An Overview of Data Utilization
- How to Use Python to Parse XML Files
How to Parse HTML: Steps to Take
Now that you know what HTML parser tasks are and why to do them, you may want to find a simple way to get this type of work done. We can offer a solution. Rayobyte’s Web Scraping API can do the work for you – and that includes handling the parsing of data from the HTML part of web scraping, which can sometimes be the more challenging part of the process.
Rayobyte’s web scraping API is a custom scraping tool that you can use for any business applications, no matter how big or small your project is. It also does not require a huge budget to make it possible.
When you use Rayobyte’s web scraping API, you benefit in several ways. It is a tool that is built for developers, which means that it will provide a structured JSON output from the metadata of the parsed website. It is also a hassle-free method of scraping. You do not have to worry about some of the big risks of this process, such as CAPTCHAs or blocks. It also has proxy management built into it, which means your IP address is protected, and you do not have to think twice about that part of the process.At Rayobyte, we aim to make web scraping as simple and straightforward as possible. If you need help getting started, check out our web scraper API and proxy services. Contact us for more information.
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