How to Parse HTML in JavaScript

Parsing data is a common process that requires careful attention to detail. If you have a significant amount of data that you need to organize and allocate, perhaps to make decisions with, you need a fast way to pull out the important components from raw information.

The HTML parser Node.js is one of the tools you can use to master this process if you want to parse HTML in JavaScript.

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Once you learn how to engage in JavaScript HTML parse tasks, you can capture valuable data to use for numerous projects with ease. Parsing HTML data allows developers to interact with web pages programmatically.

There are many ways to parse data, including parsing data in HTML. However, in the methods we focus on here, we will discuss the library that lets you parse HTML with ease – node.js. If you have a large number of HTML pages you need to parse, and you want to use JavaScript to do so, check out this guide that breaks down the process for you.

JavaScript HTML Parse: Know Your Options

It is important for developers to know they have various options when it comes to parseHTML in JS. That is, there are various methods you can use to achieve this goal. Libraries such as DOMParser and Cheerio are some examples of this. Jsdom and Parse5 are additional examples.

However, in this guide, we will focus on HTML-Parser Node.js. Node.js is an open-source JavaScript runtime environment. This cross-platform tool executes JavaScript code without the need of a browser. As a result, it provides developers with a server-side scripting tool to use JavaScript. It typically is used to build scalable applications.

It is designed to build scalable applications. If you are one of the many people who are using this process to parse data from web scraping tasks, then you may know the value of Node.js overall. The automatic data extraction tool allows you to pull valuable information in a direct way. In fact, we encourage you to read our guide on how to do so, “Web Scraping with Node JS: Automatic Data Extraction From the Internet.” 

There are several reasons why Node.js may be ideal. It is event-driven and lightweight. It is a server-side runtime environment that is non-synchronous as well. Overall, it allows you to run JavaScript code on numerous parallel connections within a server. This is why so many use it. It also offers a large package repository called npm, or Node Package Manager. This offers numerous beneficial libraries and modules that you can import into projects for web scraping. 

What to Know to Parse HTML in JavaScript 

The HTML parser in Node.js is a tool or a library that allows you to analyze and manipulate HTML content in a Node.js environment. Let’s break down what that means.

It is very common to need to parse HTML data. Parsing is the process of taking large amounts of data and breaking it into smaller pieces or chunks that can be used for a vast array of tasks. In short, parsing HTML allows you to pull out very specific components of the HTML data that you must use for specific tasks and projects. When you parse HTML, you can:

• Extract data from the raw data available to you online, such as from a web scraping project you are completing.
• Modify the elements of that HTML in a way that is meaningful to your project
• Interact with the web pages programmatically to create improved outcomes. 

HTML parsing in JavaScript can be challenging in some environments simply because of the dynamic content that is available today. However, with HTML-parser Node.js, you gain the opportunity to have a more flexible and versatile solution.

How to Parse HTML in JavaScript Using Libraries

So, how can HTML-parser Node.js work for you? Within Node.js, there are several popular libraries, which are banks of information and pre-written code that you can easily implement into your project to achieve your various tasks. Libraries make it far more efficient to scrape data and, of course, to write code for a wide range of tasks. 

The following are some of the most effective parseHTML JavaScript libraries that can be useful in most applications and needs today:

Cheerio

There are several reasons why you might want to use Cheerio. It is a fast and flexible implementation method for jQuery that is designed specifically for the server. In short, it looks like and acts like jQuery, but there is no browser to use. It can parse HTML and make it super easy to manipulate that information as you need to. Note that it does not make things happen. It will not interpret the HTML as another tool would on a browser. That means that it does not parse things differently than if it were on a browser. 

The creation of Cheerio was done because the developer wanted a lightweight alternative to jsdom. Let’s take a look at what the syntax for Cheerio looks like – and it should look pretty close to any JavaScript you’ve written before:

const cheerio = require('cheerio'),

    $ = cheerio.load('<h3 class="title">Hello there!</h3>');

$('h3.title').text('N nobody is here!');

$('h3').attr('id', 'new_id');

$.html();

//=> <h3 class="title" id="new_id">Nobody is here!</h3>

Jsdom

Another option is to use jsdom, which is a pure JavaScript implementation that is quite standard. Specifically, the WHATWG DOM and HTML Standards are met with this tool for use with Node.js. It is a powerful HTML parser. And, as the direct opposite of Cheerio, it works as a browser. It has various benefits and applications, but when it comes to HTML parsing, it allows you to automatically add the necessary tags in situations where they are not there, or make other changes. 

You can specify properties, such as the URL of the document or the user agent. If you are parsing links, for example, that contain local URLs, this can be beneficial. As a JS HTML parser, you may find numerous recommendations for using jsdom over other products and solutions. There is good reason to do so.

Here’s a look at what the syntax looks like for jsdom:

const jsdom = require("jsdom");

const { JSDOM } = jsdom;

const dom = new JSDOM('<!DOCTYPE html><p>Hello, world</p>');

console.log(dom.window.document.querySelector("p").textContent);

// => "Hello, world"

htmlparser2

Another route to consider is HTMLParser2. It is a fast and rather forgiving HTML parser (and it does XML as well). It is considered one of the faster options when it comes to parsing HTML. There is a learning curve to using it, but most people will find that there are shortcuts available. For example, if you want to parse RSS, RDF, or Atom feeds, you could do that by using this example of a parseFeed using HTMLPARSER2:

const feed = htmlparser2.parseFeed(content, options)

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DOMParser

With native DOM manipulation abilities in JavaScript and jQuery, you have a simple method for parsing HTML built into the system. However, there are times when you will need to parse a complete HTML source in a DOM document programmatically. DOMParser does this better than using the native DOM. It allows you to easily parse the HTML document without a lot of work.

Take a look at what the DOMParser usage might be for your project:

let domParser = new DOMParser();

let doc = domParser.parseFromString(stringContainingXMLSource, "application/xml");

// returns a Document, but not a SVGDocument and not a HTMLDocument

domParser = new DOMParser();

doc = domParser.parseFromString(stringContainingSVGSource, "image/svg+xml");

// returns a SVGDocument, which also is a Document.

domParser = new DOMParser();

doc = domParser.parseFromString(stringContainingHTMLSource, "text/html");

// returns a HTMLDocument, which also is a Document.

Parse5

A final example is the Parse5 library. It is a robust library that offers a great deal of flexibility for most HTML tasks. When it comes to building other tools, Parse5 is a commonly used library. However, you can use it to parse HTML for specific but simple tasks. It does not provide the methods that the browser gives you, though, which means you cannot manipulate the DOM as you would in other tools. 

It is also a bit more difficult to use overall. There is limited documentation. It is basically a series of questions that will be answered with an API reference. 

Here’s a look at what the syntax looks like:

const parse5 = require('parse5');

const document = parse5.parse('<!DOCTYPE html><html><head></head><body>Hello there!</body></html>');

console.log(document.childNodes[1].tagName); //=> 'html'

ParseHTML JavaScript Details

Each of these libraries provides developers and business owners with a simple way to parse HTML. The libraries selected and mentioned here are also beneficial because they are efficient, which means they do not take up a lot of your time to get the job done.

By being able to quickly parse HTML, it is possible to traverse the DOM, getting the specific details that you need for your current project, and do so with the ability to manipulate the structure of the HTML document itself. As you learn how to parse HTML in JavaScript, try out several of these libraries to find the one that works for the type of content you want to use or, simply, based on the way you like to navigate and build solutions.

Answering Your Questions About HTML Parsing JavaScript

When it comes to HTML-parser Node.js, there are a wide range of questions asked. 

Why are HTML parsers used? There are various reasons why HTML-parser Mode.js would be used. One of the most common reasons to do so is for web scraping. If you are gathering a significant amount of data from the internet to make decisions from – whether it is for product launch or product reviews, you need a fast and efficient strategy to get around JavaScript limitations. To see some of those details, check out our guide, “The Ultimate Guide to Node.js Web Scraping for Enterprise.”

Why Parse HTML String JavaScript? Parsing an HTML string in JavaScript is not an uncommon task. To do so, you will need to convert the string to a structured as well as traversable object. Most of the time, this means a DOM tree. In doing so, you are then able to manipulate and extract the key information from HTML content dynamically. 

What about JavaScript Json Parse string? The JSON.parse() will parse a JSON string. It does this following JSON rules. It will then evaluate the string if it’s a JavaScript expression.

What other uses are there to parsehtml in JavaScript? Web scraping may be one of the most common reasons for engaging in this process, but there are others. For example, you can use this method for automated testing. You can also use it to render content for server-side applications. Overall, it can be a dynamic tool to use for a variety of tasks. 

When you use any of these parsers, you can interact with the web data in an efficient manner. More so, with HTML parsing in JavaScript mastered, you’ll find it’s also possible to automate tasks, which means getting more done without the same amount of time commitment. Of course, the core benefit is to handle dynamic content with ease. This is a common need as more websites become dynamic.

Getting Started with HTML Parsing in JavaScript

While you can use the resources above to help you get started with HTML-parser Node.js, it is also helpful for you to get on board with Rayobyte. We offer some of the most important tools to help you build success. Start with using our web scraping API to help you capture the data you want and need online. By using our web scraping API, you cut out a lot of the complexity of this process and get the information you need sooner. Do not overlook protecting yourself using our IP proxy services as well. Contact Rayobyte for answers to all of your questions. Let our team help you gather data properly.

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