diff --git a/js/misc/params.js b/js/misc/params.js
index 8eb6eeb21..3ff8480d2 100644
--- a/js/misc/params.js
+++ b/js/misc/params.js
@@ -25,6 +25,5 @@ export function parse(params = {}, defaults, allowExtras) {
         }
     }
 
-    let defaultsCopy = Object.assign({}, defaults);
-    return Object.assign(defaultsCopy, params);
+    return {...defaults, ...params};
 }
diff --git a/js/ui/barLevel.js b/js/ui/barLevel.js
index 1b4b7f940..3f4535725 100644
--- a/js/ui/barLevel.js
+++ b/js/ui/barLevel.js
@@ -38,11 +38,11 @@ export const BarLevel = GObject.registerClass({
         this._barLevelActiveBorderColor = null;
         this._barLevelOverdriveBorderColor = null;
 
-        let defaultParams = {
+        super._init({
             style_class: 'barlevel',
             accessible_role: Atk.Role.LEVEL_BAR,
-        };
-        super._init(Object.assign(defaultParams, params));
+            ...params,
+        });
         this.connect('notify::allocation', () => {
             this._barLevelWidth = this.allocation.get_width();
         });
diff --git a/js/ui/dialog.js b/js/ui/dialog.js
index bb0084203..11a27a020 100644
--- a/js/ui/dialog.js
+++ b/js/ui/dialog.js
@@ -176,12 +176,12 @@ export const MessageDialogContent = GObject.registerClass({
         this._description.clutter_text.ellipsize = Pango.EllipsizeMode.NONE;
         this._description.clutter_text.line_wrap = true;
 
-        let defaultParams = {
+        super._init({
             style_class: 'message-dialog-content',
             x_expand: true,
             vertical: true,
-        };
-        super._init(Object.assign(defaultParams, params));
+            ...params,
+        });
 
         this.connect('notify::size', this._updateTitleStyle.bind(this));
         this.connect('destroy', this._onDestroy.bind(this));
@@ -269,12 +269,12 @@ export const ListSection = GObject.registerClass({
             child: this.list,
         });
 
-        let defaultParams = {
+        super._init({
             style_class: 'dialog-list',
             x_expand: true,
             vertical: true,
-        };
-        super._init(Object.assign(defaultParams, params));
+            ...params,
+        });
 
         this.label_actor = this._title;
         this.add_child(this._title);
@@ -327,8 +327,10 @@ export const ListSectionItem = GObject.registerClass({
         textLayout.add_child(this._title);
         textLayout.add_child(this._description);
 
-        let defaultParams = {style_class: 'dialog-list-item'};
-        super._init(Object.assign(defaultParams, params));
+        super._init({
+            style_class: 'dialog-list-item',
+            ...params,
+        });
 
         this.label_actor = this._title;
         this.add_child(this._iconActorBin);
diff --git a/js/ui/dnd.js b/js/ui/dnd.js
index 22e45766c..ea904ff42 100644
--- a/js/ui/dnd.js
+++ b/js/ui/dnd.js
@@ -795,13 +795,14 @@ class _Draggable extends Signals.EventEmitter {
         this._animationInProgress = true;
 
         // start the animation
-        this._dragActor.ease(Object.assign(params, {
+        this._dragActor.ease({
+            ...params,
             opacity: this._dragOrigOpacity,
             mode: Clutter.AnimationMode.EASE_OUT_QUAD,
             onComplete: () => {
                 this._onAnimationComplete(this._dragActor, eventTime);
             },
-        }));
+        });
     }
 
     _finishAnimation() {
diff --git a/js/ui/environment.js b/js/ui/environment.js
index 4eea5f13f..6a2b60864 100644
--- a/js/ui/environment.js
+++ b/js/ui/environment.js
@@ -211,13 +211,14 @@ function _easeActorProperty(actor, propName, target, params) {
     }
 
     let pspec = actor.find_property(propName);
-    let transition = new Clutter.PropertyTransition(Object.assign({
+    let transition = new Clutter.PropertyTransition({
         property_name: propName,
         interval: new Clutter.Interval({value_type: pspec.value_type}),
         remove_on_complete: true,
         repeat_count: repeatCount,
         auto_reverse: autoReverse,
-    }, params));
+        ...params,
+    });
     actor.add_transition(propName, transition);
 
     transition.set_to(target);
diff --git a/js/ui/lightbox.js b/js/ui/lightbox.js
index 577484137..199f562f8 100644
--- a/js/ui/lightbox.js
+++ b/js/ui/lightbox.js
@@ -209,12 +209,13 @@ export const Lightbox = GObject.registerClass({
                 '@effects.radial.brightness', VIGNETTE_BRIGHTNESS, easeProps);
             this.ease_property(
                 '@effects.radial.sharpness', VIGNETTE_SHARPNESS,
-                Object.assign({onComplete}, easeProps));
+                {onComplete, ...easeProps});
         } else {
-            this.ease(Object.assign(easeProps, {
+            this.ease({
+                ...easeProps,
                 opacity: 255 * this._fadeFactor,
                 onComplete,
-            }));
+            });
         }
     }
 
@@ -235,9 +236,9 @@ export const Lightbox = GObject.registerClass({
             this.ease_property(
                 '@effects.radial.brightness', 1.0, easeProps);
             this.ease_property(
-                '@effects.radial.sharpness', 0.0, Object.assign({onComplete}, easeProps));
+                '@effects.radial.sharpness', 0.0, {onComplete, ...easeProps});
         } else {
-            this.ease(Object.assign(easeProps, {opacity: 0, onComplete}));
+            this.ease({...easeProps, opacity: 0, onComplete});
         }
     }
 
diff --git a/js/ui/shellEntry.js b/js/ui/shellEntry.js
index 65c811168..3c924f42f 100644
--- a/js/ui/shellEntry.js
+++ b/js/ui/shellEntry.js
@@ -168,8 +168,10 @@ export function addContextMenu(entry, params) {
 export const CapsLockWarning = GObject.registerClass(
 class CapsLockWarning extends St.Label {
     _init(params) {
-        let defaultParams = {style_class: 'caps-lock-warning-label'};
-        super._init(Object.assign(defaultParams, params));
+        super._init({
+            style_class: 'caps-lock-warning-label',
+            ...params,
+        });
 
         this.text = _('Caps lock is on.');