PHP animate on scroll (AOS) helper function.

README.md

Basic usage

<div class="text" <?php aos( 'fade-up' ); ?>>
  ...
</div>

Additional settings

<div class="text" <?php aos( [
  'name' => 'fade-up',
  'anchor-placement' => 'center-center'
] ); ?>>
  ...
</div>

Conditional settings

<?php
  $aos_settings = [
    'name' => 'fade-up',
    'anchor-placement' => !empty( $placement ) ? $placement : null // `null` values removed.
  ];
?>
<div class="text" <?php aos( $aos_settings ); ?>>
  ...
</div>

aos.php

<?php
/**
 * Print/return inline AOS animation attributes.
 *
 * @param string|array $settings
 * @param bool $echo
 * @return string|null
 */
function aos( $settings = [], $echo = true ) {

	// Set default attribute values here
	$detaults = [
		'duration' => 4000
	];

	$data = [];

	if ( is_string( $settings ) ) {
		$data[ 'name' ] = $settings;
	} else if ( is_array( $settings ) ) {
		$data = $settings;
	}

	// Merge defaults
	$data = array_merge( $detaults, $data );

	// Cleaned data
	$cleaned = [];

	// Clean and remove duplicates
	foreach ( $data as $key => $value ) {
		// Remove prepending data-aos- and aos-
		$key = strtolower( $key );
		$key = preg_replace( '/^data-aos|^aos/', '', $key );
		$key = ltrim( $key, '-' );
		$key = '-' . $key;

		// Remove key if is name
		if ( $key === '-name' ) {
			$key = '';
		}

		$key = 'data-aos' . $key;

		// Overrides previous value if exists
		$cleaned[ $key ] = $value;
	}
	
	// Remove empty values
	$cleaned = array_filter( $cleaned );

	// Join key values for HTML
	$values = array_map( function( $key, $value ) {
		return $key . '="' . $value . '"';
	}, array_keys( $cleaned ), array_values( $cleaned ) );

	// Create html stirng
	$html = implode( ' ', $values );

	if ( $echo ) {
		if ( trim( $html ) ) {
			echo $html;
		}
	} else {
		return $html;
	}
}