improve effect plugin

Author: alexander.farkas

plugins/blur-up/README.md

@@ -1,4 +1,4 @@
-# The lazysizes Blur Up plugin
+# The lazysizes Blur Up/effect plugin plugin
 
 The lazysizes Blur Up plugin ([demo](https://jsfiddle.net/trixta/v0oq0412/embedded/result/)) gives you the possibility to also lazyload the low quality placeholder and enables you to create a blur up/fade over effect.
 

plugins/blur-up/ls.blur-up.js

@@ -29,10 +29,11 @@
 
 	var getLowSrc = function (picture, img) {
 		var sources = picture ? slice.call(picture.querySelectorAll('source, img')) : [img];
-
-		return sources.find(function (src) {
+		var element = sources.find(function (src) {
 			return src.getAttribute('data-lowsrc') && matchesMedia(src);
-		}).getAttribute('data-lowsrc');
+		});
+
+		return element && element.getAttribute('data-lowsrc');
 	};
 
 	var createBlurup = function(picture, img, src, blurUp){
@@ -135,7 +136,7 @@
 					return;
 				}
 
-				lazySizes.aC(img || blurImg, 'ls-inview');
+				lazySizes.aC(blurImg || img, 'ls-inview');
 
 				setStateUp();