node-html-parser

What is node-html-parser?

The node-html-parser package is a fast HTML parser designed for Node.js, which allows users to parse HTML documents and manipulate the resulting DOM tree. It provides an API to navigate and modify the DOM, extract data, and serialize DOM back to HTML.

What are node-html-parser's main functionalities?

Parsing HTML string to DOM

This feature allows you to parse a string containing HTML and creates a DOM tree that can be manipulated. The example code demonstrates parsing an HTML string and logging the structure of the first child element.

const { parse } = require('node-html-parser');
const root = parse('<ul id="list"><li>Hello World</li></ul>');
console.log(root.firstChild.structure);

Querying the DOM

This feature enables querying the DOM tree for elements using selectors. The code sample shows how to select the first 'li' element and log its text content.

const { parse } = require('node-html-parser');
const root = parse('<ul id="list"><li>Hello World</li></ul>');
const listItem = root.querySelector('li');
console.log(listItem.text);

Modifying the DOM

This feature allows you to modify the DOM tree by changing the content of elements. In the example, the content of the 'li' element is changed from 'Hello World' to 'Hello Universe', and the updated HTML is logged.

const { parse } = require('node-html-parser');
const root = parse('<ul id="list"><li>Hello World</li></ul>');
const listItem = root.querySelector('li');
listItem.set_content('Hello Universe');
console.log(root.toString());

Serializing DOM back to HTML

After manipulating the DOM, you can serialize it back to an HTML string. The code sample demonstrates how to convert the DOM tree back into an HTML string and log it.

const { parse } = require('node-html-parser');
const root = parse('<div><p>Hello World</p></div>');
const html = root.toString();
console.log(html);

Other packages similar to node-html-parser

cheerio

Cheerio is a fast, flexible, and lean implementation of core jQuery designed specifically for the server. It provides a familiar jQuery interface to traverse and manipulate the DOM. Compared to node-html-parser, cheerio offers a more extensive API and is more widely used for web scraping and server-side DOM manipulation.

jsdom

jsdom is a pure-JavaScript implementation of many web standards, notably the WHATWG DOM and HTML Standards, for use with Node.js. It is more heavyweight compared to node-html-parser as it aims to provide a comprehensive simulation of a web browser's environment. jsdom is suitable for more complex tasks that require a full DOM API and the ability to execute scripts.

parse5

parse5 is an HTML parsing/serialization toolset for Node.js that adheres to the HTML5 specification. It is designed to be a spec-compliant parsing library, which makes it suitable for projects that require high standards of HTML parsing accuracy. Compared to node-html-parser, parse5 may be slower but offers better standards compliance.

README

Fast HTML Parser

Fast HTML Parser is a very fast HTML parser. Which will generate a simplified DOM tree, with element query support.

Per the design, it intends to parse massive HTML files in lowest price, thus the performance is the top priority. For this reason, some malformatted HTML may not be able to parse correctly, but most usual errors are covered (eg. HTML4 style no closing <li>, <td> etc).

Install

npm install --save node-html-parser

Note: when using Fast HTML Parser in a Typescript project the minimum Typescript version supported is ^4.1.2.

Performance

-- 2022-08-10

html-parser     :24.1595 ms/file ± 18.7667
htmljs-parser   :4.72064 ms/file ± 5.67689
html-dom-parser :2.18055 ms/file ± 2.96136
html5parser     :1.69639 ms/file ± 2.17111
cheerio         :12.2122 ms/file ± 8.10916
parse5          :6.50626 ms/file ± 4.02352
htmlparser2     :2.38179 ms/file ± 3.42389
htmlparser      :17.4820 ms/file ± 128.041
high5           :3.95188 ms/file ± 2.52313
node-html-parser:2.04288 ms/file ± 1.25203
node-html-parser (last release):2.00527 ms/file ± 1.21317

Tested with htmlparser-benchmark.

Usage

import { parse } from 'node-html-parser';

const root = parse('<ul id="list"><li>Hello World</li></ul>');

console.log(root.firstChild.structure);
// ul#list
//   li
//     #text

console.log(root.querySelector('#list'));
// { tagName: 'ul',
//   rawAttrs: 'id="list"',
//   childNodes:
//    [ { tagName: 'li',
//        rawAttrs: '',
//        childNodes: [Object],
//        classNames: [] } ],
//   id: 'list',
//   classNames: [] }
console.log(root.toString());
// <ul id="list"><li>Hello World</li></ul>
root.set_content('<li>Hello World</li>');
root.toString();	// <li>Hello World</li>

var HTMLParser = require('node-html-parser');

var root = HTMLParser.parse('<ul id="list"><li>Hello World</li></ul>');

Global Methods

parse(data[, options])

Parse the data provided, and return the root of the generated DOM.

• data, data to parse

• options, parse options

  {
    lowerCaseTagName: false,  // convert tag name to lower case (hurts performance heavily)
    comment: false,            // retrieve comments (hurts performance slightly)
    voidTag:{
      tags: ['area', 'base', 'br', 'col', 'embed', 'hr', 'img', 'input', 'link', 'meta', 'param', 'source', 'track', 'wbr'],	// optional and case insensitive, default value is ['area', 'base', 'br', 'col', 'embed', 'hr', 'img', 'input', 'link', 'meta', 'param', 'source', 'track', 'wbr']
      addClosingSlash: true     // optional, default false. void tag serialisation, add a final slash <br/>
    },
    blockTextElements: {
      script: true,	// keep text content when parsing
      noscript: true,	// keep text content when parsing
      style: true,		// keep text content when parsing
      pre: true			// keep text content when parsing
    }
  }
  

valid(data[, options])

Parse the data provided, return true if the given data is valid, and return false if not.

HTMLElement Methods

HTMLElement#trimRight()

Trim element from right (in block) after seeing pattern in a TextNode.

HTMLElement#removeWhitespace()

Remove whitespaces in this sub tree.

HTMLElement#querySelectorAll(selector)

Query CSS selector to find matching nodes.

Note: Full range of CSS3 selectors supported since v3.0.0.

HTMLElement#querySelector(selector)

Query CSS Selector to find matching node.

HTMLElement#getElementsByTagName(tagName)

Get all elements with the specified tagName.

Note: Use * for all elements.

HTMLElement#closest(selector)

Query closest element by css selector.

HTMLElement#appendChild(node)

Append a child node to childNodes

HTMLElement#insertAdjacentHTML(where, html)

Parses the specified text as HTML and inserts the resulting nodes into the DOM tree at a specified position.

HTMLElement#setAttribute(key: string, value: string)

Set value to key attribute.

HTMLElement#setAttributes(attrs: Record<string, string>)

Set attributes of the element.

HTMLElement#removeAttribute(key: string)

Remove key attribute.

HTMLElement#getAttribute(key: string)

Get key attribute.

HTMLElement#exchangeChild(oldNode: Node, newNode: Node)

Exchanges given child with new child.

HTMLElement#removeChild(node: Node)

Remove child node.

HTMLElement#toString()

Same as outerHTML

HTMLElement#set_content(content: string | Node | Node[])

Set content. Notice: Do not set content of the root node.

HTMLElement#remove()

Remove current element.

HTMLElement#replaceWith(...nodes: (string | Node)[])

Replace current element with other node(s).

HTMLElement#classList

HTMLElement#classList.add

Add class name.

HTMLElement#classList.replace(old: string, new: string)

Replace class name with another one.

HTMLElement#classList.remove()

Remove class name.

HTMLElement#classList.toggle(className: string):void

Toggle class. Remove it if it is already included, otherwise add.

HTMLElement#classList.contains(className: string): boolean

Returns true if the classname is already in the classList.

HTMLElement#classList.values()

Get class names.

Node#clone()

Clone a node.

Node#getElementById(id: string): HTMLElement;

Get element by it's ID.

HTMLElement Properties

HTMLElement#text

Get unescaped text value of current node and its children. Like innerText. (slow for the first time)

HTMLElement#rawText

Get escaped (as-is) text value of current node and its children. May have & in it. (fast)

HTMLElement#tagName

Get or Set tag name of HTMLElement. Notice: the returned value would be an uppercase string.

HTMLElement#structuredText

Get structured Text.

HTMLElement#structure

Get DOM structure.

HTMLElement#firstChild

Get first child node.

HTMLElement#lastChild

Get last child node.

HTMLElement#innerHTML

Set or Get innerHTML.

HTMLElement#outerHTML

Get outerHTML.

HTMLElement#nextSibling

Returns a reference to the next child node of the current element's parent.

HTMLElement#nextElementSibling

Returns a reference to the next child element of the current element's parent.

HTMLElement#previousSibling

Returns a reference to the previous child node of the current element's parent.

HTMLElement#previousElementSibling

Returns a reference to the previous child element of the current element's parent.

HTMLElement#textContent

Get or Set textContent of current element, more efficient than set_content.

HTMLElement#attributes

Get all attributes of current element. Notice: do not try to change the returned value.

HTMLElement#classList

Get all attributes of current element. Notice: do not try to change the returned value.

HTMLElement#range

Corresponding source code start and end indexes (ie [ 0, 40 ])