The get_tag_regex() WordPress PHP function returns a RegEx pattern to liberally match an opening HTML tag.
Usage
get_tag_regex($tag);
Example:
Input:
get_tag_regex('video');
Output:
<(video)[\s\w<>=\/\!]*>
Parameters
$tag (string)– Required. An HTML tag name. Example:'video'.
More information
See WordPress Developer Resources: get_tag_regex()
Examples
Match Image Tags
Find all opening image tags in a string.
$content = 'Here is an image <img src="image.jpg" alt="An Image"> and another <img src="another.jpg" alt="Another Image">';
$regex = get_tag_regex('img');
preg_match_all("/$regex/", $content, $matches);
print_r($matches);
Match Paragraph Tags
Find all opening paragraph tags in a string.
$content = '<p>Hello, world!</p><p>Another paragraph here</p>';
$regex = get_tag_regex('p');
preg_match_all("/$regex/", $content, $matches);
print_r($matches);
Match Custom Tags
Find all opening custom tags in a string.
$content = '<custom-tag>Some content</custom-tag><custom-tag>Another content</custom-tag>';
$regex = get_tag_regex('custom-tag');
preg_match_all("/$regex/", $content, $matches);
print_r($matches);
Match Anchor Tags
Find all opening anchor tags in a string.
$content = 'Visit our <a href="https://example.com">website</a> and <a href="https://example.com/contact">contact us</a>';
$regex = get_tag_regex('a');
preg_match_all("/$regex/", $content, $matches);
print_r($matches);
Match Header Tags
Find all opening header tags (h1, h2, h3) in a string.
$content = '<h1>Title</h1><h2>Subtitle</h2><h3>Section</h3>';
$header_tags = ['h1', 'h2', 'h3'];
foreach ($header_tags as $tag) {
$regex = get_tag_regex($tag);
preg_match_all("/$regex/", $content, $matches);
print_r($matches);
}