Extracting Flat Text from Elements with a Designated Class Using PHP DOM

Extracting text from specific HTML elements is a common task in web development. PHP DOM provides robust tools for parsing HTML and accessing its contents. This article addresses a specific requirement to extract text from elements with a nominated class into two flat arrays.

Problem

Given HTML content containing text distributed between multiple p elements with alternating class names, the task is to save the text into two arrays: one for headings and one for content. For instance, given the following HTML:

    Chapter 1


    This is chapter 1

We need to obtain the following output:

$heading = ['Chapter 1', 'Chapter 2', 'Chapter 3'];
$content = ['This is chapter 1', 'This is chapter 2', 'This is chapter 3'];

Solution

To accomplish this extraction using PHP DOM, we employ DOMDocument and DOMXPath. The solution involves the following steps:

1. Load the HTML into a DOMDocument object:

$dom = new DOMDocument();
$dom->loadHTML($test);

2. Create a DOMXPath object to perform XPaths:

$xpath = new DOMXPath($dom);

3. Use parseToArray() function to extract text from elements with specified class:

$heading = parseToArray($xpath, 'Heading1-H');
$content = parseToArray($xpath, 'Normal-H');

In the parseToArray() function:

• It performs an XPath query for the designated class.
• Iterates through the matched nodes and extracts their text content.
• Stores the extracted text in an array, which is returned.

Here's the complete PHP code:

query($xpathquery);

    $resultarray = [];
    foreach ($elements as $element) {
        $nodes = $element->childNodes;
        foreach ($nodes as $node) {
            $resultarray[] = $node->nodeValue;
        }
    }

    return $resultarray;
}

$test = 
    Chapter 1


    This is chapter 1


    Chapter 2


    This is chapter 2


    Chapter 3


    This is chapter 3

HTML;

$dom = new DOMDocument();
$dom->loadHTML($test);
$xpath = new DOMXPath($dom);
$heading = parseToArray($xpath, 'Heading1-H');
$content = parseToArray($xpath, 'Normal-H');

var_dump($heading);
echo "
";
var_dump($content);
echo "
";

This approach utilizes the power of PHP DOM and XPath to efficiently extract text from HTML documents, allowing for more complex and targeted content manipulation.