Changeset 58143

Timestamp:

05/13/2024 10:37:38 PM (5 months ago)

Author:

westonruter

Message:

Embeds: Enable lazy-loading of post embeds and fix keyboard a11y for hidden iframes.

Chrome unreliably loads a lazy-loaded iframe when it is hidden using clip: rect(1px, 1px, 1px, 1px). Instead of using clip, a lazy-loaded iframe can also be hidden with visibility:hidden which results in it loading not only in Chrome but all other browsers. With this change applied, the hard-coded check to prevent lazy-loading post embeds is now removed. An added benefit to using visibility:hidden is that the entire iframe in this case is not interactable, meaning that users navigating the document with the keyboard will not unexpectedly encounter tab stops inside of the hidden iframe, as can happen now with clip when the JS fails to reveal the loaded iframe. Note also that the clip property is deprecated.

Lastly, when such a post embed iframe is rendered in an RSS feed, the style attribute is now removed using the HTML Tag Processor as opposed to using string replacement.

Fixes #58773.
Props westonruter, joemcgill, swissspidy, joedolson, adamsilverstein.

Location:

trunk

Files:

• src/wp-includes/embed.php (modified) (2 diffs)
• src/wp-includes/media.php (modified) (1 diff)
• tests/phpunit/tests/media.php (modified) (2 diffs)
• tests/phpunit/tests/oembed/filterResult.php (modified) (4 diffs)
• tests/phpunit/tests/oembed/template.php (modified) (2 diffs)

trunk/src/wp-includes/embed.php

@@ -967 +967 @@
     if ( ! empty( $content[1] ) ) {
         // We have a blockquote to fall back on. Hide the iframe by default.
-        $html = str_replace( '<iframe', '<iframe style="position: absolute; clip: rect(1px, 1px, 1px, 1px);"', $html );
+        $html = str_replace( '<iframe', '<iframe style="position: absolute; visibility: hidden;"', $html );
         $html = str_replace( '<blockquote', '<blockquote class="wp-embedded-content"', $html );
     }
@@ -1100 +1100 @@
  */
 function _oembed_filter_feed_content( $content ) {
-    return str_replace( '<iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; clip: rect(1px, 1px, 1px, 1px);"', '<iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted"', $content );
+    $p = new WP_HTML_Tag_Processor( $content );
+    while ( $p->next_tag( array( 'tag_name' => 'iframe' ) ) ) {
+        if ( $p->has_class( 'wp-embedded-content' ) ) {
+            $p->remove_attribute( 'style' );
+        }
+    }
+    return $p->get_updated_html();
 }
 

trunk/src/wp-includes/media.php

@@ -2198 +2198 @@
  */
 function wp_iframe_tag_add_loading_attr( $iframe, $context ) {
-    /*
-     * Iframes with fallback content (see `wp_filter_oembed_result()`) should not be lazy-loaded because they are
-     * visually hidden initially.
-     */
-    if ( str_contains( $iframe, ' data-secret="' ) ) {
-        return $iframe;
-    }
-
     /*
      * Get loading attribute value to use. This must occur before the conditional check below so that even iframes that

trunk/tests/phpunit/tests/media.php

@@ -3258 +3258 @@
     /**
      * @ticket 52768
-     */
-    public function test_wp_iframe_tag_add_loading_attr_skip_wp_embed() {
+     * @ticket 58773
+     */
+    public function test_wp_iframe_tag_add_loading_attr_include_wp_embed() {
         $iframe   = '<iframe src="https://www.example.com" width="640" height="360"></iframe>';
         $fallback = '<blockquote>Fallback content.</blockquote>';
@@ -3265 +3266 @@
         $iframe   = wp_iframe_tag_add_loading_attr( $iframe, 'test' );
 
-        $this->assertStringNotContainsString( ' loading=', $iframe );
+        $this->assertStringContainsString( ' loading="lazy"', $iframe );
     }
 

trunk/tests/phpunit/tests/oembed/filterResult.php

@@ -84 +84 @@
         $actual = wp_filter_oembed_result( $html, (object) array( 'type' => 'rich' ), '' );
 
-        $this->assertSame( '<blockquote class="wp-embedded-content"></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; clip: rect(1px, 1px, 1px, 1px);"></iframe>', $actual );
+        $this->assertSame( '<blockquote class="wp-embedded-content"></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; visibility: hidden;"></iframe>', $actual );
     }
 
@@ -91 +91 @@
         $actual = wp_filter_oembed_result( $html, (object) array( 'type' => 'rich' ), '' );
 
-        $this->assertSame( '<blockquote class="wp-embedded-content"><a href=""></a></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; clip: rect(1px, 1px, 1px, 1px);"></iframe>', $actual );
+        $this->assertSame( '<blockquote class="wp-embedded-content"><a href=""></a></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; visibility: hidden;"></iframe>', $actual );
     }
 
@@ -98 +98 @@
             array(
                 '<blockquote></blockquote><iframe title=""></iframe>',
-                '<blockquote class="wp-embedded-content"></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; clip: rect(1px, 1px, 1px, 1px);" title="Hola"></iframe>',
+                '<blockquote class="wp-embedded-content"></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; visibility: hidden;" title="Hola"></iframe>',
             ),
             array(
                 '<blockquote class="foo" id="bar"><strong><a href="" target=""></a></strong></blockquote><iframe width=123></iframe>',
-                '<blockquote class="wp-embedded-content"><a href=""></a></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; clip: rect(1px, 1px, 1px, 1px);" title="Hola" width="123"></iframe>',
+                '<blockquote class="wp-embedded-content"><a href=""></a></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; visibility: hidden;" title="Hola" width="123"></iframe>',
             ),
             array(
                 '<blockquote><iframe width="100"></iframe></blockquote><iframe stitle="aaaa"></iframe>',
-                '<blockquote class="wp-embedded-content"><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; clip: rect(1px, 1px, 1px, 1px);" title="Hola" width="100"></iframe></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; clip: rect(1px, 1px, 1px, 1px);" title="Hola"></iframe>',
+                '<blockquote class="wp-embedded-content"><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; visibility: hidden;" title="Hola" width="100"></iframe></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; visibility: hidden;" title="Hola"></iframe>',
             ),
             array(
                 "<blockquote><iframe title=' width=\"'></iframe></blockquote><iframe title='' height=' title=' width=\"'' height='123'\"></iframe>",
-                '<blockquote class="wp-embedded-content"><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; clip: rect(1px, 1px, 1px, 1px);" title=" width=&quot;"></iframe></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; clip: rect(1px, 1px, 1px, 1px);" title=" width=&quot;" height=\' title=\' width="\'\' height=\'123\'"></iframe>',
+                '<blockquote class="wp-embedded-content"><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; visibility: hidden;" title=" width=&quot;"></iframe></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; visibility: hidden;" title=" width=&quot;" height=\' title=\' width="\'\' height=\'123\'"></iframe>',
             ),
         );
@@ -135 +135 @@
         $actual = _oembed_filter_feed_content( wp_filter_oembed_result( $html, (object) array( 'type' => 'rich' ), '' ) );
 
-        $this->assertSame( '<blockquote class="wp-embedded-content"></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted"></iframe>', $actual );
+        $this->assertSame( '<blockquote class="wp-embedded-content"></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" ></iframe>', $actual );
     }
 }

trunk/tests/phpunit/tests/oembed/template.php

@@ -322 +322 @@
         $this->assertFalse( $scripts->query( 'wp-embed', 'enqueued' ) );
 
-        $post_embed     = '<blockquote class="wp-embedded-content" data-secret="S24AQCJW9i"><a href="https://make.wordpress.org/core/2016/03/11/embeds-changes-in-wordpress-4-5/">Embeds Changes in WordPress 4.5</a></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; clip: rect(1px, 1px, 1px, 1px);" title="&#8220;Embeds Changes in WordPress 4.5&#8221; &#8212; Make WordPress Core" src="https://make.wordpress.org/core/2016/03/11/embeds-changes-in-wordpress-4-5/embed/#?secret=S24AQCJW9i" data-secret="S24AQCJW9i" width="600" height="338" frameborder="0" marginwidth="0" marginheight="0" scrolling="no"></iframe>';
+        $post_embed     = '<blockquote class="wp-embedded-content" data-secret="S24AQCJW9i"><a href="https://make.wordpress.org/core/2016/03/11/embeds-changes-in-wordpress-4-5/">Embeds Changes in WordPress 4.5</a></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; visibility: hidden;" title="&#8220;Embeds Changes in WordPress 4.5&#8221; &#8212; Make WordPress Core" src="https://make.wordpress.org/core/2016/03/11/embeds-changes-in-wordpress-4-5/embed/#?secret=S24AQCJW9i" data-secret="S24AQCJW9i" width="600" height="338" frameborder="0" marginwidth="0" marginheight="0" scrolling="no"></iframe>';
         $non_post_embed = '<iframe title="Zoo Cares For 23 Tiny Pond Turtles" width="750" height="422" src="https://www.youtube.com/embed/6ZXHqUjL6f8?feature=oembed" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>';
 
@@ -339 +339 @@
         $this->assertFalse( $scripts->query( 'wp-embed', 'enqueued' ) );
 
-        $post_embed = '<blockquote class="wp-embedded-content" data-secret="S24AQCJW9i"><a href="https://make.wordpress.org/core/2016/03/11/embeds-changes-in-wordpress-4-5/">Embeds Changes in WordPress 4.5</a></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; clip: rect(1px, 1px, 1px, 1px);" title="&#8220;Embeds Changes in WordPress 4.5&#8221; &#8212; Make WordPress Core" src="https://make.wordpress.org/core/2016/03/11/embeds-changes-in-wordpress-4-5/embed/#?secret=S24AQCJW9i" data-secret="S24AQCJW9i" width="600" height="338" frameborder="0" marginwidth="0" marginheight="0" scrolling="no"></iframe>';
+        $post_embed = '<blockquote class="wp-embedded-content" data-secret="S24AQCJW9i"><a href="https://make.wordpress.org/core/2016/03/11/embeds-changes-in-wordpress-4-5/">Embeds Changes in WordPress 4.5</a></blockquote><iframe class="wp-embedded-content" sandbox="allow-scripts" security="restricted" style="position: absolute; visibility: hidden;" title="&#8220;Embeds Changes in WordPress 4.5&#8221; &#8212; Make WordPress Core" src="https://make.wordpress.org/core/2016/03/11/embeds-changes-in-wordpress-4-5/embed/#?secret=S24AQCJW9i" data-secret="S24AQCJW9i" width="600" height="338" frameborder="0" marginwidth="0" marginheight="0" scrolling="no"></iframe>';
 
         wp_maybe_enqueue_oembed_host_js( $post_embed );