diff --git a/docs/Function_Init3DViewerElements.html b/docs/Function_Init3DViewerElements.html
index 3f871c4..dfd33d9 100644
--- a/docs/Function_Init3DViewerElements.html
+++ b/docs/Function_Init3DViewerElements.html
@@ -61,16 +61,13 @@
 <div id="main" class="main">
 <h1>Init3DViewerElements</h1>
 <div class="function_container">
-<div id="Init3DViewerElements" class="function_signature">Init3DViewerElements (onReady)</div>
+<div id="Init3DViewerElements" class="function_signature">Init3DViewerElements ()</div>
 <div class="function_title">Description</div>
-<div class="function_description">Loads all the models on the page. This function looks for all the elements with online_3d_viewer class name, and loads the model according to the tag&#x27;s parameters.</div>
-<div class="function_title">Parameters</div>
-<div class="parameter_header">
-<span class="parameter_name">onReady</span>
-<span class="type parameter_type">function</span>
-</div>
-<div class="parameter_main">
-<div class="parameter_description">Callback that called when all models are loaded. It has one parameter that is an array of the created <a href="Class_EmbeddedViewer.html" target="_self">EmbeddedViewer</a> objects.</div>
+<div class="function_description">Loads all the models on the page. This function looks for all the elements with online_3d_viewer class name, and loads the model according to the tag&#x27;s parameters. It must be called after the document is loaded.</div>
+<div class="function_title">Returns</div>
+<div class="function_returns">
+<span class="type parameter_type"><a href="Class_EmbeddedViewer.html" target="_self">EmbeddedViewer</a>[]</span>
+<span class="return_description">Array of the created <a href="Class_EmbeddedViewer.html" target="_self">EmbeddedViewer</a> objects.</span>
 </div>
 </div>
 
diff --git a/docs/Page_MigrationGuide.html b/docs/Page_MigrationGuide.html
index d34e814..57bdec1 100644
--- a/docs/Page_MigrationGuide.html
+++ b/docs/Page_MigrationGuide.html
@@ -64,6 +64,13 @@
 
 <p>This document lists changes in the engine to help you to migrate your code base.</p>
 
+<h2>0.8.21</h2>
+
+<ul>
+    <li><a href="Function_Init3DViewerElements.html" target="_self">Init3DViewerElements</a> must be called when the document is loaded and returns an array of the created <a href="Class_EmbeddedViewer.html" target="_self">EmbeddedViewer</a> objects. Earlier it registered a load event handler inside, now it's the responsibility of the caller.</li>
+</ul>
+
+
 <h2>0.8.21</h2>
 
 <ul>
diff --git a/docs/Page_Usage.html b/docs/Page_Usage.html
index 006c3d3..f61060f 100644
--- a/docs/Page_Usage.html
+++ b/docs/Page_Usage.html
@@ -92,12 +92,14 @@ There are two ways to use the library:
     <li><b>environmentmapbg:</b> Boolean ("true" or "false") to set the environment map as background.</li>
 </ul>
 
-<p>After placing the elements, call the <a href="Function_Init3DViewerElements.html" target="_self">Init3DViewerElements</a> function to initalize all the viewers. It must be called from the main JavaScript file outside of the onload event.</p>
+<p>After placing the elements, call the <a href="Function_Init3DViewerElements.html" target="_self">Init3DViewerElements</a> function to initalize all the viewers. It must be called after the document is loaded.</p>
 
-<pre><code class="language-js">// tell the engine where to find the libs folder
-OV.SetExternalLibLocation ('libs');
-// init all viewers on the page
-OV.Init3DViewerElements ();</code></pre>
+<pre><code class="language-js">window.addEventListener ('load', () => {
+    // tell the engine where to find the libs folder
+    OV.SetExternalLibLocation ('libs');
+    // init all viewers on the page
+    OV.Init3DViewerElements ();
+});</code></pre>
 
 <h2>Initialization from code</h2>
 
diff --git a/docs/source/MigrationGuide.html b/docs/source/MigrationGuide.html
index 46cfa45..bd48c5d 100644
--- a/docs/source/MigrationGuide.html
+++ b/docs/source/MigrationGuide.html
@@ -2,6 +2,13 @@
 
 <p>This document lists changes in the engine to help you to migrate your code base.</p>
 
+<h2>0.8.21</h2>
+
+<ul>
+    <li>{@link Init3DViewerElements} must be called when the document is loaded and returns an array of the created {@link EmbeddedViewer} objects. Earlier it registered a load event handler inside, now it's the responsibility of the caller.</li>
+</ul>
+
+
 <h2>0.8.21</h2>
 
 <ul>
diff --git a/docs/source/Usage.html b/docs/source/Usage.html
index 4951a1d..1b66ed6 100644
--- a/docs/source/Usage.html
+++ b/docs/source/Usage.html
@@ -30,12 +30,14 @@ There are two ways to use the library:
     <li><b>environmentmapbg:</b> Boolean ("true" or "false") to set the environment map as background.</li>
 </ul>
 
-<p>After placing the elements, call the {@link Init3DViewerElements} function to initalize all the viewers. It must be called from the main JavaScript file outside of the onload event.</p>
+<p>After placing the elements, call the {@link Init3DViewerElements} function to initalize all the viewers. It must be called after the document is loaded.</p>
 
-<pre><code class="language-js">// tell the engine where to find the libs folder
-OV.SetExternalLibLocation ('libs');
-// init all viewers on the page
-OV.Init3DViewerElements ();</code></pre>
+<pre><code class="language-js">window.addEventListener ('load', () => {
+    // tell the engine where to find the libs folder
+    OV.SetExternalLibLocation ('libs');
+    // init all viewers on the page
+    OV.Init3DViewerElements ();
+});</code></pre>
 
 <h2>Initialization from code</h2>
 
diff --git a/sandbox/embed_background.html b/sandbox/embed_background.html
index c12460a..8aad587 100644
--- a/sandbox/embed_background.html
+++ b/sandbox/embed_background.html
@@ -10,7 +10,9 @@
 	<script type="text/javascript" src="../build/o3dv.min-dev.js"></script>
 
     <script type='text/javascript'>
-        OV.Init3DViewerElements ();
+        window.addEventListener ('load', () => {
+            OV.Init3DViewerElements ();
+        });
     </script>
 
     <style>
diff --git a/sandbox/embed_camera.html b/sandbox/embed_camera.html
index bab1ec4..9f254a8 100644
--- a/sandbox/embed_camera.html
+++ b/sandbox/embed_camera.html
@@ -10,7 +10,10 @@
 	<script type="text/javascript" src="../build/o3dv.min-dev.js"></script>
 
     <script type='text/javascript'>
-        OV.Init3DViewerElements ();
+        window.addEventListener ('load', () => {
+            OV.Init3DViewerElements ();
+        });
+
     </script>
 
     <style>
diff --git a/sandbox/embed_edges.html b/sandbox/embed_edges.html
index 57d83bf..f4de27f 100644
--- a/sandbox/embed_edges.html
+++ b/sandbox/embed_edges.html
@@ -10,7 +10,9 @@
 	<script type="text/javascript" src="../build/o3dv.min-dev.js"></script>
 
     <script type='text/javascript'>
-        OV.Init3DViewerElements ();
+        window.addEventListener ('load', () => {
+            OV.Init3DViewerElements ();
+        });
     </script>
 
     <style>
diff --git a/sandbox/embed_filehost.html b/sandbox/embed_filehost.html
index 3ccb211..465a689 100644
--- a/sandbox/embed_filehost.html
+++ b/sandbox/embed_filehost.html
@@ -10,7 +10,9 @@
 	<script type="text/javascript" src="../build/o3dv.min-dev.js"></script>
 
     <script type='text/javascript'>
-        OV.Init3DViewerElements ();
+        window.addEventListener ('load', () => {
+            OV.Init3DViewerElements ();
+        });
     </script>
 
     <style>
diff --git a/sandbox/embed_iframe_envmaps.html b/sandbox/embed_iframe_envmaps.html
index eeb4fc8..da2cb50 100644
--- a/sandbox/embed_iframe_envmaps.html
+++ b/sandbox/embed_iframe_envmaps.html
@@ -10,8 +10,10 @@
 	<script type="text/javascript" src="../build/o3dv.min-dev.js"></script>
 
     <script type='text/javascript'>
-        OV.SetExternalLibLocation ('../../libs');
-        OV.Init3DViewerElements ();
+        window.addEventListener ('load', () => {
+            OV.SetExternalLibLocation ('../../libs');
+            OV.Init3DViewerElements ();
+        });
     </script>
 
     <style>
diff --git a/sandbox/embed_selfhost_errors.html b/sandbox/embed_selfhost_errors.html
index a402739..b22891a 100644
--- a/sandbox/embed_selfhost_errors.html
+++ b/sandbox/embed_selfhost_errors.html
@@ -10,7 +10,9 @@
 	<script type="text/javascript" src="../build/o3dv.min-dev.js"></script>
 
     <script type='text/javascript'>
-        OV.Init3DViewerElements ();
+        window.addEventListener ('load', () => {
+            OV.Init3DViewerElements ();
+        });
     </script>
 
     <style>
diff --git a/sandbox/embed_selfhost_externallibs.html b/sandbox/embed_selfhost_externallibs.html
index 05e8dd1..ff0ff32 100644
--- a/sandbox/embed_selfhost_externallibs.html
+++ b/sandbox/embed_selfhost_externallibs.html
@@ -10,8 +10,10 @@
 	<script type="text/javascript" src="../build/o3dv.min-dev.js"></script>
 
     <script type='text/javascript'>
-        OV.SetExternalLibLocation ('../../libs');
-        OV.Init3DViewerElements ();
+        window.addEventListener ('load', () => {
+            OV.SetExternalLibLocation ('../../libs');
+            OV.Init3DViewerElements ();
+        });
     </script>
 
     <style>
diff --git a/sandbox/embed_selfhost_fullscreen.html b/sandbox/embed_selfhost_fullscreen.html
index a3bd7bf..8ac9447 100644
--- a/sandbox/embed_selfhost_fullscreen.html
+++ b/sandbox/embed_selfhost_fullscreen.html
@@ -10,7 +10,9 @@
 	<script type="text/javascript" src="../build/o3dv.min-dev.js"></script>
 
     <script type='text/javascript'>
-        OV.Init3DViewerElements ();
+        window.addEventListener ('load', () => {
+            OV.Init3DViewerElements ();
+        });
     </script>
 
     <style>
diff --git a/sandbox/embed_selfhost_multiple.html b/sandbox/embed_selfhost_multiple.html
index a057ee7..f0571ad 100644
--- a/sandbox/embed_selfhost_multiple.html
+++ b/sandbox/embed_selfhost_multiple.html
@@ -10,10 +10,11 @@
 	<script type="text/javascript" src="../build/o3dv.min-dev.js"></script>
 
     <script type='text/javascript'>
-        OV.Init3DViewerElements (function (viewers) {
+        window.addEventListener ('load', () => {
+            let viewers = OV.Init3DViewerElements ();
 			let firstViewer = viewers[0].viewer;
 			firstViewer.SetBackgroundColor (new OV.RGBAColor (34, 34, 34, 255));
-		});
+        });
     </script>
 
     <style>
diff --git a/sandbox/embed_selfhost_multiple_2.html b/sandbox/embed_selfhost_multiple_2.html
index 10e7467..37c6dc2 100644
--- a/sandbox/embed_selfhost_multiple_2.html
+++ b/sandbox/embed_selfhost_multiple_2.html
@@ -10,7 +10,9 @@
 	<script type="text/javascript" src="../build/o3dv.min-dev.js"></script>
 
     <script type='text/javascript'>
-        OV.Init3DViewerElements ();
+        window.addEventListener ('load', () => {
+            OV.Init3DViewerElements ();
+        });
     </script>
 
     <style>
diff --git a/sandbox/embed_selfhost_single.html b/sandbox/embed_selfhost_single.html
index f986d88..bfd3697 100644
--- a/sandbox/embed_selfhost_single.html
+++ b/sandbox/embed_selfhost_single.html
@@ -10,7 +10,9 @@
 	<script type="text/javascript" src="../build/o3dv.min-dev.js"></script>
 
     <script type='text/javascript'>
-        OV.Init3DViewerElements ();
+        window.addEventListener ('load', () => {
+            OV.Init3DViewerElements ();
+		});
     </script>
 </head>
 
diff --git a/sandbox/embed_selfhost_single_scroll.html b/sandbox/embed_selfhost_single_scroll.html
index b2398c1..0c8c138 100644
--- a/sandbox/embed_selfhost_single_scroll.html
+++ b/sandbox/embed_selfhost_single_scroll.html
@@ -10,7 +10,9 @@
 	<script type="text/javascript" src="../build/o3dv.min-dev.js"></script>
 
     <script type='text/javascript'>
-        OV.Init3DViewerElements ();
+        window.addEventListener ('load', () => {
+            OV.Init3DViewerElements ();
+		});
     </script>
 </head>
 
diff --git a/source/engine/viewer/embeddedviewer.js b/source/engine/viewer/embeddedviewer.js
index d9ba4c2..2f075bb 100644
--- a/source/engine/viewer/embeddedviewer.js
+++ b/source/engine/viewer/embeddedviewer.js
@@ -243,9 +243,9 @@ export function Init3DViewerFromFileList (parentElement, models, parameters)
 
 /**
  * Loads all the models on the page. This function looks for all the elements with online_3d_viewer
- * class name, and loads the model according to the tag's parameters.
- * @param {function} onReady Callback that called when all models are loaded. It has one parameter
- * that is an array of the created {@link EmbeddedViewer} objects.
+ * class name, and loads the model according to the tag's parameters. It must be called after the
+ * document is loaded.
+ * @returns {EmbeddedViewer[]} Array of the created {@link EmbeddedViewer} objects.
  */
 export function Init3DViewerElements (onReady)
 {
@@ -312,15 +312,11 @@ export function Init3DViewerElements (onReady)
     }
 
     let viewerElements = [];
-    window.addEventListener ('load', () => {
-        let elements = document.getElementsByClassName ('online_3d_viewer');
-        for (let i = 0; i < elements.length; i++) {
-            let element = elements[i];
-            let viewerElement = LoadElement (element);
-            viewerElements.push (viewerElement);
-        }
-        if (onReady !== undefined && onReady !== null) {
-            onReady (viewerElements);
-        }
-    });
+    let elements = document.getElementsByClassName ('online_3d_viewer');
+    for (let i = 0; i < elements.length; i++) {
+        let element = elements[i];
+        let viewerElement = LoadElement (element);
+        viewerElements.push (viewerElement);
+    }
+    return viewerElements;
 }