diff --git a/examples/heatmap-earthquakes.js b/examples/heatmap-earthquakes.js
index 953f596946..05d28aeb31 100644
--- a/examples/heatmap-earthquakes.js
+++ b/examples/heatmap-earthquakes.js
@@ -43,11 +43,14 @@ const map = new Map({
   })
 });
 
-
-blur.addEventListener('input', function() {
+const blurHandler = function() {
   vector.setBlur(parseInt(blur.value, 10));
-});
+};
+blur.addEventListener('input', blurHandler);
+blur.addEventListener('change', blurHandler);
 
-radius.addEventListener('input', function() {
+const radiusHandler = function() {
   vector.setRadius(parseInt(radius.value, 10));
-});
+};
+radius.addEventListener('input', radiusHandler);
+radius.addEventListener('change', radiusHandler);
diff --git a/src/ol/webgl/Helper.js b/src/ol/webgl/Helper.js
index af5daa0fe7..504db3342a 100644
--- a/src/ol/webgl/Helper.js
+++ b/src/ol/webgl/Helper.js
@@ -18,6 +18,7 @@ import {
 } from '../transform';
 import {create, fromTransform} from '../vec/mat4';
 import WebGLPostProcessingPass from './PostProcessingPass';
+import {getContext} from '../webgl';
 
 
 /**
@@ -220,7 +221,7 @@ class WebGLHelper extends Disposable {
      * @private
      * @type {WebGLRenderingContext}
      */
-    this.gl_ = this.canvas_.getContext('webgl');
+    this.gl_ = getContext(this.canvas_);
     const gl = this.getGL();
 
     /**