Add lazy loading to question embed iframes #776130

Author: Jason.Platts

templates/embed_iframe.mustache

@@ -36,7 +36,7 @@
     }
 }}
 <iframe
-    class="filter_embedquestion-iframe" allowfullscreen
+    class="filter_embedquestion-iframe" allowfullscreen loading="lazy"
     title="{{iframedescription}}"
     src="{{{showquestionurl}}}"
     id="{{embedid}}"{{#name}} name="{{name}}"{{/name}}></iframe>

tests/filter_test.php

@@ -79,7 +79,7 @@ public static function get_cases_for_test_filter(): array {
         $cases['defaultoptions'] = [
             '{Q{cat/q|' . $requiredtoken . '}Q}',
             '<iframe
-    class="filter_embedquestion-iframe" allowfullscreen
+    class="filter_embedquestion-iframe" allowfullscreen loading="lazy"
     title="' . $title . '"
     src="' . $expectedurl . '"
     id="cat/q"></iframe>',
@@ -110,7 +110,7 @@ class="filter_embedquestion-iframe" allowfullscreen
                 'behaviour=immediatefeedback|marks=10|markdp=3|generalfeedback=0|forcedlanguage=en|' .
                 $requiredtoken . '}Q}',
                 '<iframe
-    class="filter_embedquestion-iframe" allowfullscreen
+    class="filter_embedquestion-iframe" allowfullscreen loading="lazy"
     title="' . $title . '"
     src="' . $expectedurl . '"
     id="AVquestions/---100"></iframe>',