PHP Parse HTML Code

PHP Parse HTML code

Use PHP Document Object Model:

<?php
   $str = '<h1>T1</h1>Lorem ipsum.<h1>T2</h1>The quick red fox...<h1>T3</h1>... jumps over the lazy brown FROG';
   $DOM = new DOMDocument;
   $DOM->loadHTML($str);

   //get all H1
   $items = $DOM->getElementsByTagName('h1');

   //display all H1 text
   for ($i = 0; $i < $items->length; $i++)
        echo $items->item($i)->nodeValue . "<br/>";
?>

This outputs as:

 T1
 T2
 T3

[EDIT]: After OP Clarification:

If you want the content like Lorem ipsum. etc, you can directly use this regex:

<?php
   $str = '<h1>T1</h1>Lorem ipsum.<h1>T2</h1>The quick red fox...<h1>T3</h1>... jumps over the lazy brown FROG';
   echo preg_replace("#<h1.*?>.*?</h1>#", "", $str);
?>

this outputs:

Lorem ipsum.The quick red fox...... jumps over the lazy brown FROG

PHP parse HTML tags

You would be looking at something like this:

<?php
$content = "";
$doc = new DOMDocument();
$doc->load("example.html");
$items = $doc->getElementsByTagName('tag1');
if(count($items) > 0) //Only if tag1 items are found 
{
    foreach ($items as $tag1)
    {
         // Do something with $tag1->nodeValue and save your modifications
         $content .= $tag1->nodeValue;
    }
}
else
{
     $content = $doc->saveHTML();
}
echo $content;
?>

DomDocument represents an entire HTML or XML document; serves as the root of the document tree. So you will have a valid markup, and by finding elements By Tag Name you won't find comments.

How do you parse and process HTML/XML in PHP?

Native XML Extensions

I prefer using one of the native XML extensions since they come bundled with PHP, are usually faster than all the 3rd party libs and give me all the control I need over the markup.

DOM

The DOM extension allows you to operate on XML documents through the DOM API with PHP 5. It is an implementation of the W3C's Document Object Model Core Level 3, a platform- and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure and style of documents.

DOM is capable of parsing and modifying real world (broken) HTML and it can do XPath queries. It is based on libxml.

It takes some time to get productive with DOM, but that time is well worth it IMO. Since DOM is a language-agnostic interface, you'll find implementations in many languages, so if you need to change your programming language, chances are you will already know how to use that language's DOM API then.

How to use the DOM extension has been covered extensively on StackOverflow, so if you choose to use it, you can be sure most of the issues you run into can be solved by searching/browsing Stack Overflow.

A basic usage example and a general conceptual overview are available in other answers.

XMLReader

The XMLReader extension is an XML pull parser. The reader acts as a cursor going forward on the document stream and stopping at each node on the way.

XMLReader, like DOM, is based on libxml. I am not aware of how to trigger the HTML Parser Module, so chances are using XMLReader for parsing broken HTML might be less robust than using DOM where you can explicitly tell it to use libxml's HTML Parser Module.

A basic usage example is available in another answer.

XML Parser

This extension lets you create XML parsers and then define handlers for different XML events. Each XML parser also has a few parameters you can adjust.

The XML Parser library is also based on libxml, and implements a SAX style XML push parser. It may be a better choice for memory management than DOM or SimpleXML, but will be more difficult to work with than the pull parser implemented by XMLReader.

SimpleXml

The SimpleXML extension provides a very simple and easily usable toolset to convert XML to an object that can be processed with normal property selectors and array iterators.

SimpleXML is an option when you know the HTML is valid XHTML. If you need to parse broken HTML, don't even consider SimpleXml because it will choke.

A basic usage example is available, and there are lots of additional examples in the PHP Manual.

3rd Party Libraries (libxml based)

If you prefer to use a 3rd-party lib, I'd suggest using a lib that actually uses DOM/libxml underneath instead of string parsing.

FluentDom

FluentDOM provides a jQuery-like fluent XML interface for the DOMDocument in PHP. Selectors are written in XPath or CSS (using a CSS to XPath converter). Current versions extend the DOM implementing standard interfaces and add features from the DOM Living Standard. FluentDOM can load formats like JSON, CSV, JsonML, RabbitFish and others. Can be installed via Composer.

HtmlPageDom

Wa72\HtmlPageDom is a PHP library for easy manipulation of HTML
documents using DOM. It requires DomCrawler from Symfony2
components for traversing
the DOM tree and extends it by adding methods for manipulating the
DOM tree of HTML documents.

phpQuery

phpQuery is a server-side, chainable, CSS3 selector driven Document Object Model (DOM) API based on jQuery JavaScript Library.
The library is written in PHP5 and provides additional Command Line Interface (CLI).

This is described as "abandonware and buggy: use at your own risk" but does appear to be minimally maintained.

laminas-dom

The Laminas\Dom component (formerly Zend_DOM) provides tools for working with DOM documents and structures. Currently, we offer Laminas\Dom\Query, which provides a unified interface for querying DOM documents utilizing both XPath and CSS selectors.
This package is considered feature-complete, and is now in security-only maintenance mode.

fDOMDocument

fDOMDocument extends the standard DOM to use exceptions at all occasions of errors instead of PHP warnings or notices. They also add various custom methods and shortcuts for convenience and to simplify the usage of DOM.

sabre/xml

sabre/xml is a library that wraps and extends the XMLReader and XMLWriter classes to create a simple "xml to object/array" mapping system and design pattern. Writing and reading XML is single-pass and can therefore be fast and require low memory on large xml files.

FluidXML

FluidXML is a PHP library for manipulating XML with a concise and fluent API.
It leverages XPath and the fluent programming pattern to be fun and effective.

3rd-Party (not libxml-based)

The benefit of building upon DOM/libxml is that you get good performance out of the box because you are based on a native extension. However, not all 3rd-party libs go down this route. Some of them listed below

PHP Simple HTML DOM Parser

An HTML DOM parser written in PHP5+ lets you manipulate HTML in a very easy way!
Require PHP 5+.
Supports invalid HTML.
Find tags on an HTML page with selectors just like jQuery.
Extract contents from HTML in a single line.

I generally do not recommend this parser. The codebase is horrible and the parser itself is rather slow and memory hungry. Not all jQuery Selectors (such as child selectors) are possible. Any of the libxml based libraries should outperform this easily.

PHP Html Parser

PHPHtmlParser is a simple, flexible, html parser which allows you to select tags using any css selector, like jQuery. The goal is to assiste in the development of tools which require a quick, easy way to scrape html, whether it's valid or not! This project was original supported by sunra/php-simple-html-dom-parser but the support seems to have stopped so this project is my adaptation of his previous work.

Again, I would not recommend this parser. It is rather slow with high CPU usage. There is also no function to clear memory of created DOM objects. These problems scale particularly with nested loops. The documentation itself is inaccurate and misspelled, with no responses to fixes since 14 Apr 16.

HTML 5

You can use the above for parsing HTML5, but there can be quirks due to the markup HTML5 allows. So for HTML5 you may want to consider using a dedicated parser. Note that these are written in PHP, so suffer from slower performance and increased memory usage compared to a compiled extension in a lower-level language.

HTML5DomDocument

HTML5DOMDocument extends the native DOMDocument library. It fixes some bugs and adds some new functionality.
Preserves html entities (DOMDocument does not)
Preserves void tags (DOMDocument does not)
Allows inserting HTML code that moves the correct parts to their proper places (head elements are inserted in the head, body elements in the body)
Allows querying the DOM with CSS selectors (currently available: *, tagname, tagname#id, #id, tagname.classname, .classname, tagname.classname.classname2, .classname.classname2, tagname[attribute-selector], [attribute-selector], div, p, div p, div > p, div + p, and p ~ ul.)
Adds support for element->classList.
Adds support for element->innerHTML.
Adds support for element->outerHTML.

HTML5

HTML5 is a standards-compliant HTML5 parser and writer written entirely in PHP. It is stable and used in many production websites, and has well over five million downloads.
HTML5 provides the following features.

An HTML5 serializer
Support for PHP namespaces
Composer support
Event-based (SAX-like) parser
A DOM tree builder
Interoperability with QueryPath
Runs on PHP 5.3.0 or newer

Regular Expressions

Last and least recommended, you can extract data from HTML with regular expressions. In general using Regular Expressions on HTML is discouraged.

Most of the snippets you will find on the web to match markup are brittle. In most cases they are only working for a very particular piece of HTML. Tiny markup changes, like adding whitespace somewhere, or adding, or changing attributes in a tag, can make the RegEx fails when it's not properly written. You should know what you are doing before using RegEx on HTML.

HTML parsers already know the syntactical rules of HTML. Regular expressions have to be taught for each new RegEx you write. RegEx are fine in some cases, but it really depends on your use-case.

You can write more reliable parsers, but writing a complete and reliable custom parser with regular expressions is a waste of time when the aforementioned libraries already exist and do a much better job on this.

Also see Parsing Html The Cthulhu Way

Books

If you want to spend some money, have a look at

PHP Architect's Guide to Webscraping with PHP

I am not affiliated with PHP Architect or the authors.

How to parse HTML in PHP?

Try to look at PHP Simple HTML DOM Parser

It has brilliant syntax similar to jQuery so you can easily select any element you want by ID or class

// include/require the simple html dom parser file

$html_string = '
    <p class="Heading1-P">
        <span class="Heading1-H">Chapter 1</span>
    </p>
    <p class="Normal-P">
        <span class="Normal-H">This is chapter 1</span>
    </p>
    <p class="Heading1-P">
        <span class="Heading1-H">Chapter 2</span>
    </p>
    <p class="Normal-P">
        <span class="Normal-H">This is chapter 2</span>
    </p>
    <p class="Heading1-P">
        <span class="Heading1-H">Chapter 3</span>
    </p>
    <p class="Normal-P">
        <span class="Normal-H">This is chapter 3</span>
    </p>';
$html = str_get_html($html_string);
foreach($html->find('span') as $element) {
    if ($element->class === 'Heading1-H') {
        $heading[] = $element->innertext;
    }else if($element->class === 'Normal-H') {
        $content[] = $element->innertext;
    }
}

PHP - Parse HTML, Select tag, Insert another HTML string inside selected tag

Found a solution, selected an item(0) from elements stored in $items, and called appendChild() on it, thanks to @NigelRen

$first_mark = $items->item(0);
$first_mark->appendChild($gear);

parse the html data to array data in php

I will do it using DOMDocument and DOMXPath to target interesting parts more easily. In order to be more precise, I register a function that checks if a class attribute contains a set of classes:

function hasClasses($attrValue, $requiredClasses) {
    $requiredClasses = explode(' ', $requiredClasses);
    $classes = preg_split('~\s+~', $attrValue, -1, PREG_SPLIT_NO_EMPTY);
    return array_diff($requiredClasses, $classes) ? false : true;
}

$dom = new DOMDocument;
$state = libxml_use_internal_errors(true);
$dom->loadHTML($html);
libxml_use_internal_errors($state);

$xp = new DOMXPath($dom);
$xp->registerNamespace('php', 'http://php.net/xpath');
$xp->registerPhpFunctions('hasClasses');

$mainDivClasses = 'result results_links results_links_deep web-result';
$childDivClasses = 'links_main links_deep result__body';

$divNodeList = $xp->query('//div[php:functionString("hasClasses", @class, "' . $mainDivClasses . '")]
                           /div[php:functionString("hasClasses", @class, "' . $childDivClasses . '")]');

$results = [];
foreach ($divNodeList as $divNode) {
    $results[] = [
        trim($xp->evaluate('string(./h2/a[@class="result__a"])', $divNode)),
        trim($xp->evaluate('string(.//a[@class="result__snippet"])', $divNode)),
        trim($xp->evaluate('string(.//a[@class="result__url"])', $divNode))
    ];
}

print_r($results);

without registering a function, you can also use the XPath function contains in your predicates. It's less precise since it only checks if a substring is in a larger string (and not if a class attribute have a specific class like the hasClasses function) but it must be enough:

$dom = new DOMDocument;
$state = libxml_use_internal_errors(true);
$dom->loadHTML($html);
libxml_use_internal_errors($state);

$xp = new DOMXPath($dom);

$divNodeList = $xp->query('//div[contains(@class, "results_links_deep")]
                                [contains(@class, "web-result")]
                           /div[contains(@class, "links_main")]
                               [contains(@class, "links_deep")]
                               [contains(@class, "result__body")]');

$results = [];
foreach ($divNodeList as $divNode) {
    $results[] = [
        trim($xp->evaluate('string(./h2/a[@class="result__a"])', $divNode)),
        trim($xp->evaluate('string(.//a[@class="result__snippet"])', $divNode)),
        trim($xp->evaluate('string(.//a[@class="result__url"])', $divNode))
    ];
}

print_r($results);

Efficient way to parse html in PHP?

It's generally not good idea to parse HTML/XML with regexp. There are lot of special situations which regexp cannot handle - the tag split into several lines, & entities, CDATA and many others.

The real parser (either DOM or SAX if the text is actually xml) is quite quick and the reliability is incomparable.

PHP Parse HTML Code