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authorMax Rothman <max@collegevine.com>2019-03-19 22:28:30 -0400
committerMax Rothman <max@collegevine.com>2019-03-22 10:45:08 -0400
commit93b1abc7364eacb028c30f145603d0a155f2fcbd (patch)
tree7eb0e9939d9d91f6bd462f7284338e0e8ef9e39b /js
parentc7db11d9cfeb7984f643af3effb1fea5865ce4cc (diff)
downloadperl-software-in-gnu-guix-93b1abc7364eacb028c30f145603d0a155f2fcbd.tar
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Add data-preload attribute for iframes
Allows lazy-loaded (i.e. data-src) iframes to be preloaded when they come within the viewDistance, rather than once they're visible.
Diffstat (limited to 'js')
-rw-r--r--js/reveal.js54
1 files changed, 47 insertions, 7 deletions
diff --git a/js/reveal.js b/js/reveal.js
index 387077a..662679b 100644
--- a/js/reveal.js
+++ b/js/reveal.js
@@ -3672,6 +3672,26 @@
}
/**
+ * Should the given element be preloaded?
+ * Decides based on local element attributes and global config.
+ *
+ * @param {HTMLElement} element
+ */
+ function shouldPreload(element) {
+
+ // Prefer an explicit global preload setting
+ var preload = config.preloadIframes;
+
+ // If no global setting is available, fall back on the element's
+ // own preload setting
+ if( typeof preload !== 'boolean' ) {
+ preload = element.hasAttribute( 'data-preload' );
+ }
+
+ return preload;
+ }
+
+ /**
* Called when the given slide is within the configured view
* distance. Shows the slide element and loads any content
* that is set to load lazily (data-src).
@@ -3686,10 +3706,20 @@
slide.style.display = config.display;
// Media elements with data-src attributes
- toArray( slide.querySelectorAll( 'img[data-src], video[data-src], audio[data-src]' ) ).forEach( function( element ) {
- element.setAttribute( 'src', element.getAttribute( 'data-src' ) );
- element.setAttribute( 'data-lazy-loaded', '' );
- element.removeAttribute( 'data-src' );
+ toArray( slide.querySelectorAll( 'img[data-src], video[data-src], audio[data-src], iframe[data-src]' ) ).forEach( function( element ) {
+ var load = function( el ) {
+ el.setAttribute( 'src', el.getAttribute( 'data-src' ) );
+ el.setAttribute( 'data-lazy-loaded', '' );
+ el.removeAttribute( 'data-src' );
+ };
+
+ if( element.tagName === 'IFRAME') {
+ if( shouldPreload(element) ) {
+ load(element);
+ }
+ } else {
+ load(element);
+ }
} );
// Media elements with <source> children
@@ -3807,9 +3837,19 @@
}
// Reset lazy-loaded media elements with src attributes
- toArray( slide.querySelectorAll( 'video[data-lazy-loaded][src], audio[data-lazy-loaded][src]' ) ).forEach( function( element ) {
- element.setAttribute( 'data-src', element.getAttribute( 'src' ) );
- element.removeAttribute( 'src' );
+ toArray( slide.querySelectorAll( 'video[data-lazy-loaded][src], audio[data-lazy-loaded][src], iframe[data-lazy-loaded][src]' ) ).forEach( function( element ) {
+ var unload = function( el ) {
+ el.setAttribute( 'data-src', el.getAttribute( 'src' ) );
+ el.removeAttribute( 'src' );
+ };
+
+ if( element.tagName === 'IFRAME' ) {
+ if( shouldPreload(element) ) {
+ unload(element);
+ }
+ } else {
+ unload(element);
+ }
} );
// Reset lazy-loaded media elements with <source> children