diff --git a/Changes b/Changes
index 718613a..8776a90 100755
--- a/Changes
+++ b/Changes
@@ -33,6 +33,7 @@
         - Buttongroup menus can be opened at different positions.
         - Fix buttongroup anchoring if anchor doesn't exist.
         - Fix blind header titles.
+        - Turn "upgradeTo" into an object prototype.
 
 0.42 2021-06-18
         - Added GitHub based CI for perl.
diff --git a/dev/js/src/buttongroup.js b/dev/js/src/buttongroup.js
index dabe710..85c6555 100644
--- a/dev/js/src/buttongroup.js
+++ b/dev/js/src/buttongroup.js
@@ -64,18 +64,6 @@
       return false;
     },
     
-    /**
-     * Upgrade this object to another object, 
-     * while private data stays intact.
-     * 
-     * @param {Object} An object with properties.
-     */
-    upgradeTo : function (props) {
-      for (var prop in props) {
-        this[prop] = props[prop];
-      };
-      return this;
-    },
 
     _insert : function (tag = 'span') {
       const span = document.createElement(tag);
diff --git a/dev/js/src/container/container.js b/dev/js/src/container/container.js
index 9b436ca..60bc0d9 100644
--- a/dev/js/src/container/container.js
+++ b/dev/js/src/container/container.js
@@ -54,18 +54,6 @@
 
 
     },
-    /**
-     * Upgrade this object to another object,
-     * while private data stays intact.
-     *
-    * @param {Object} An object with properties.
-    */
-    upgradeTo : function (props) {
-      for (let prop in props) {
-        this[prop] = props[prop];
-      };
-      return this;
-    },
 
     addItem : function (item) {
       var cItem = this._containerItemClass.create().upgradeTo(item);
@@ -227,4 +215,4 @@
     }
 
 };
-});
\ No newline at end of file
+});
diff --git a/dev/js/src/container/containeritem.js b/dev/js/src/container/containeritem.js
index 10709b8..a9a209b 100644
--- a/dev/js/src/container/containeritem.js
+++ b/dev/js/src/container/containeritem.js
@@ -18,19 +18,6 @@
   },
 
   /**
-   * Upgrade this object to another object,
-   * while private data stays intact.
-   *
-   * @param {Object} An object with properties.
-   */
-  upgradeTo : function (props) {
-    for (let prop in props) {
-      this[prop] = props[prop];
-    };
-    return this;
-  },
-
-  /**
    * Check or set if the item is active
    *
    * @param {boolean|null} State of activity
@@ -105,4 +92,4 @@
     return this._menu;
   }
 
-});
\ No newline at end of file
+});
diff --git a/dev/js/src/menu.js b/dev/js/src/menu.js
index 794d517..0c84c48 100644
--- a/dev/js/src/menu.js
+++ b/dev/js/src/menu.js
@@ -485,20 +485,6 @@
 
 
     /**
-     * Upgrade this object to another object,
-     * while private data stays intact.
-     *
-     * @param {Object} An object with properties.
-     */
-    upgradeTo : function (props) {
-      for (var prop in props) {
-        this[prop] = props[prop];
-      };
-      return this;
-    },
-
-
-    /**
      * Filter the list and make it visible.
      * This is always called once the prefix changes.
      *
diff --git a/dev/js/src/menu/item.js b/dev/js/src/menu/item.js
index e369918..ea46287 100644
--- a/dev/js/src/menu/item.js
+++ b/dev/js/src/menu/item.js
@@ -25,20 +25,6 @@
 
 
   /**
-   * Upgrade this object to another object,
-   * while private data stays intact.
-   *
-   * @param {Object] An object with properties.
-   */
-  upgradeTo : function (props) {
-    for (let prop in props) {
-      this[prop] = props[prop];
-    };
-    return this;
-  },
-
-
-  /**
    * Get or set the content of the meun item.
    */
   content : function (content) {
diff --git a/dev/js/src/menu/lengthField.js b/dev/js/src/menu/lengthField.js
index eed90b7..b7891c4 100644
--- a/dev/js/src/menu/lengthField.js
+++ b/dev/js/src/menu/lengthField.js
@@ -19,20 +19,6 @@
 
 
   /**
-   * Upgrade this object to another object,
-   * while private data stays intact.
-   *
-   * @param {Object} An object with properties.
-   */
-  upgradeTo : function (props) {
-    for (let prop in props) {
-      this[prop] = props[prop];
-    };
-    return this;
-  },
-
-
-  /**
    * Get the associated dom element.
    */
   element : function () {
diff --git a/dev/js/src/menu/prefix.js b/dev/js/src/menu/prefix.js
index 20e2753..59a0ab5 100644
--- a/dev/js/src/menu/prefix.js
+++ b/dev/js/src/menu/prefix.js
@@ -36,20 +36,6 @@
 
 
   /**
-   * Upgrade this object to another object,
-   * while private data stays intact.
-   *
-   * @param {Object} An object with properties.
-   */
-  upgradeTo : function (props) {
-    for (let prop in props) {
-      this[prop] = props[prop];
-    };
-    return this;
-  },
-
-
-  /**
    * Get or set the activity status of the prefix.
    */
   active : function (bool) {
diff --git a/dev/js/src/panel.js b/dev/js/src/panel.js
index 53ea757..63eea6c 100644
--- a/dev/js/src/panel.js
+++ b/dev/js/src/panel.js
@@ -124,20 +124,6 @@
         if (e === view)
           a[i] = undefined;
       });
-    },
-
-
-    /**
-     * Upgrade this object to another object,
-     * while private data stays intact.
-     *
-     * @param {Object] An object with properties.
-     */
-    upgradeTo : function (props) {
-      for (let prop in props) {
-        this[prop] = props[prop];
-      };
-      return this;
     }
   }
 });
diff --git a/dev/js/src/util.js b/dev/js/src/util.js
index 42edf44..e227c67 100644
--- a/dev/js/src/util.js
+++ b/dev/js/src/util.js
@@ -27,6 +27,20 @@
   return this.toLowerCase().replace(_slug1RE, '').replace(_slug2RE, '-');
 };
 
+/**
+ * Upgrade this object to another object,
+ * while private data stays intact.
+ *
+ * @param {Object} An object with properties.
+ */
+Object.prototype.upgradeTo  = function (props) {
+  for (let prop in props) {
+    this[prop] = props[prop];
+  };
+  return this;
+};
+
+
 // Add toggleClass method similar to jquery
 HTMLElement.prototype.toggleClass = function (c1, c2) {
   const cl = this.classList;
@@ -201,4 +215,4 @@
   //filter by actually being direct child node
   classElements = classElements.filter(subElement => subElement.parentNode === element);
   return classElements;
-};
\ No newline at end of file
+};
diff --git a/dev/js/src/vc/jsonld.js b/dev/js/src/vc/jsonld.js
index 06be1e0..4d6b8e4 100644
--- a/dev/js/src/vc/jsonld.js
+++ b/dev/js/src/vc/jsonld.js
@@ -14,18 +14,6 @@
     },
 
 
-    /**
-     * Upgrade this object to another object
-     * while private data stays intact
-     */
-    upgradeTo : function (props) {
-      for (let prop in props) {
-	      this[prop] = props[prop];
-      };
-      return this;
-    },
-    
-
     ldType : function (type) {
       if (arguments.length === 1)
 	      this._ldType = type;
diff --git a/dev/js/src/view.js b/dev/js/src/view.js
index b45c485..326e603 100644
--- a/dev/js/src/view.js
+++ b/dev/js/src/view.js
@@ -119,20 +119,6 @@
       };
       this.panel.delView(this);
       this._shown = false;
-    },
-
-
-    /**
-     * Upgrade this object to another object,
-     * while private data stays intact.
-     *
-     * @param {Object] An object with properties.
-     */
-    upgradeTo : function (props) {
-      for (let prop in props) {
-        this[prop] = props[prop];
-      };
-      return this;
     }
   };
 });