Include amp-runtime script for Non-AMP pages.

rt-amp-enabler-for-non-amp.php

<?php
/**
 * Plugin Name: AMP Framework enabler for Non AMP.
 * Description: Enables AMP as Framework enabler for Non AMP.
 * Plugin URI: https://rtcamp.com
 * Version: 0.2
 * Author: rtCamp, pradeep910
 * Author URI: https://rtcamp.com
 *
 * @package rtCamp
 */

/**
 * AMP Init function to load scripts and styles.
 */
function rt_amp_init() {

	// Skip if current page is AMP page already.
	if ( is_admin() || ( function_exists( 'is_amp_endpoint' ) && ! is_amp_endpoint() ) ) {
		return;
	}

	// Include amp-runtime script.
	add_action( 'wp_enqueue_scripts', 'rt_load_amp_script' );

	// Add amp_boilerplate css code.
	add_action( 'wp_head', 'rt_amp_boilerplate_css' );

}

add_action( 'init', 'rt_amp_init' );

/**
 * Include amp-runtime script for AMP components.
 */
function rt_load_amp_script() {

	wp_enqueue_script( 'amp-runtime', 'https://cdn.ampproject.org/v0.js', [], null );

}

/**
 * Filter Script Loader Tag to filter scripts with async tags.
 *
 * @param string $tag    Script tag markup.
 * @param string $handle Script handle name.
 *
 * @return mixed
 */
function rt_add_script_async_attribute( $tag, $handle ) {

	// Use script handle check to add async parameter to script.
	$async_script_handle = 'amp-runtime';

	if ( $async_script_handle === $handle ) {
		return str_replace( ' src', ' async="async" src', $tag );
	}

	return $tag;
}

add_filter( 'script_loader_tag', 'rt_add_script_async_attribute', 10, 2 );

/**
 * Add AMP Boilerplate CSS
 */
function rt_amp_boilerplate_css() {

	echo '<style amp-boilerplate>body{-webkit-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-moz-animation:-amp-start 8s steps(1,end) 0s 1 normal both;-ms-animation:-amp-start 8s steps(1,end) 0s 1 normal both;animation:-amp-start 8s steps(1,end) 0s 1 normal both}@-webkit-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-moz-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-ms-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@-o-keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}@keyframes -amp-start{from{visibility:hidden}to{visibility:visible}}</style>
<noscript><style amp-boilerplate>body{-webkit-animation:none;-moz-animation:none;-ms-animation:none;animation:none}</style></noscript>'; // WPCS: xss ok.

}