Using wp_filter_content_tags to filter content tags in WordPress
The wp_filter_content_tags function in WordPress is responsible for filtering content tags within a post, page, or custom post type. This function takes the existing HTML content as its input and processes it to replace specific HTML tags with their equivalent HTML5 tags. The tags it targets for replacement include <img>, <iframe>, <video>, and <audio> tags.
The function operates by identifying these specified tags within the content and replacing them with responsive HTML5 versions. The HTML5 versions of these tags are designed to provide better compatibility with different device types and screen sizes, thereby improving the overall responsiveness of the website. This function is part of WordPress’s effort to ensure that the content it generates adheres to modern web standards.
While the wp_filter_content_tags function operates automatically on the_content and widget_text_content filters, it can also be manually applied to other text-based content that may contain the specified HTML tags.
The utility of the wp_filter_content_tags function lies in its capacity to automatically update older HTML tags to their HTML5 counterparts, thus ensuring that the content being presented is optimally responsive and compatible with a wide range of devices and screen sizes. This function plays a role in maintaining the technological relevance and usability of a WordPress site, as HTML5 has been widely adopted as the standard for modern web development.
Parameters Accepted by the wp_filter_content_tags Function
The wp_filter_content_tags function in WordPress accepts two parameters which are:
$content(string), which is required. This refers to the HTML content that needs to be filtered.$context(string), which is optional and defaults to null. This provides additional context to the filters. If not set, it defaults to the current_filter().
If the function does not accept any parameters, it will be explicitly stated.
Return Value of the wp_filter_content_tags Function
The wp_filter_content_tags function returns a string. This string represents the original content but with modifications made to the images. This means that the function takes the original HTML content, applies certain filters based on the context provided, modifies the images within the content, and then returns this newly formed content.
Examples
How to filter content tags in a post content
function filter_content_tags($content) {
return wp_filter_content_tags($content);
}
add_filter('the_content', 'filter_content_tags');
In this example, the wp_filter_content_tags function is used to filter the content of a post. The function is hooked to the ‘the_content’ filter, so it applies to all the content of all the posts. The wp_filter_content_tags function replaces the ‘img’, ‘iframe’, ‘audio’, ‘video’, ‘source’ and ‘track’ tags with ‘lazy-load’ compatible ones, improving the performance of the website.
How to apply wp_filter_content_tags function in a custom context
function filter_custom_content($content) {
return wp_filter_content_tags($content, 'custom_context');
}
add_filter('custom_content_filter', 'filter_custom_content');
In this example, the wp_filter_content_tags function is used in a custom context. The function is hooked to a custom filter ‘custom_content_filter’, so it can be applied to any content passed through this filter. The second parameter of the function is the context, which defaults to the current filter when not set. In this case, it is set to ‘custom_context’.
How to conditionally apply wp_filter_content_tags function
function filter_content_tags_conditionally($content) {
if (is_single()) {
return wp_filter_content_tags($content);
}
return $content;
}
add_filter('the_content', 'filter_content_tags_conditionally');
In this example, the wp_filter_content_tags function is applied conditionally only to single posts. The is_single() function checks if the post is a single post. If it is, it applies the wp_filter_content_tags function to the post content. If not, it returns the original content without any modifications.
Conclusion
The wp_filter_content_tags function in WordPress serves as a tool for modifying the HTML content of your website. It is used to change the ‘img’, ‘iframe’, ‘audio’, ‘video’, and ‘source’ HTML tags of your content into ‘picture’ and ‘source’ tags. This function is particularly useful for adding responsive image attributes to content, as well as for filtering and transforming the HTML tags of your content to ensure that they are compatible with various devices and screen sizes. It is an integral part of WordPress’s efforts to provide a more responsive and accessible user experience.