diff --git a/ebitenutil/loadimage_js.go b/ebitenutil/loadimage_js.go
index faab17f2f..364d9b079 100644
--- a/ebitenutil/loadimage_js.go
+++ b/ebitenutil/loadimage_js.go
@@ -27,7 +27,7 @@ import (
 
 func NewImageFromFile(path string, filter ebiten.Filter) (*ebiten.Image, image.Image, error) {
 	var err error
-	var content js.Object
+	var content *js.Object
 	ch := make(chan struct{})
 	req := js.Global.Get("XMLHttpRequest").New()
 	req.Call("open", "GET", path, true)
diff --git a/exp/audio/internal/audio_js.go b/exp/audio/internal/audio_js.go
index 7be097c66..d282c8ffa 100644
--- a/exp/audio/internal/audio_js.go
+++ b/exp/audio/internal/audio_js.go
@@ -26,9 +26,9 @@ func withChannels(f func()) {
 
 // Keep this so as not to be destroyed by GC.
 var (
-	nodes   = []js.Object{}
-	dummies = []js.Object{} // Dummy source nodes for iOS.
-	context js.Object
+	nodes   = []*js.Object{}
+	dummies = []*js.Object{} // Dummy source nodes for iOS.
+	context *js.Object
 )
 
 const bufferSize = 1024
@@ -37,7 +37,7 @@ type audioProcessor struct {
 	channel int
 }
 
-func (a *audioProcessor) Process(e js.Object) {
+func (a *audioProcessor) Process(e *js.Object) {
 	// Can't use 'go' here. Probably it may cause race conditions.
 	b := e.Get("outputBuffer")
 	l := b.Call("getChannelData", 0)
diff --git a/internal/graphics/internal/opengl/context_js.go b/internal/graphics/internal/opengl/context_js.go
index 03dfa2532..ae4dfe074 100644
--- a/internal/graphics/internal/opengl/context_js.go
+++ b/internal/graphics/internal/opengl/context_js.go
@@ -24,25 +24,25 @@ import (
 )
 
 type Texture struct {
-	js.Object
+	*js.Object
 }
 
 type Framebuffer struct {
-	js.Object
+	*js.Object
 }
 
 var ZeroFramebuffer Framebuffer
 
 type Shader struct {
-	js.Object
+	*js.Object
 }
 
 type Program struct {
-	js.Object
+	*js.Object
 }
 
 type Buffer struct {
-	js.Object
+	*js.Object
 }
 
 // TODO: Remove this after the GopherJS bug was fixed (#159)
@@ -51,7 +51,7 @@ func (p Program) Equals(other Program) bool {
 }
 
 type UniformLocation struct {
-	js.Object
+	*js.Object
 }
 
 type AttribLocation int
@@ -192,7 +192,7 @@ func (c *Context) NewFramebuffer(t Texture) (Framebuffer, error) {
 	return Framebuffer{f}, nil
 }
 
-var lastBindedFramebuffer js.Object
+var lastBindedFramebuffer *js.Object
 
 func (c *Context) SetViewport(f Framebuffer, width, height int) error {
 	// TODO: Not sure if Flush is needed here.
diff --git a/internal/ui/ui_js.go b/internal/ui/ui_js.go
index fb5113775..ce13fb1dc 100644
--- a/internal/ui/ui_js.go
+++ b/internal/ui/ui_js.go
@@ -65,7 +65,7 @@ func SetScreenScale(scale int) (bool, int) {
 	return result, actualScale
 }
 
-var canvas js.Object
+var canvas *js.Object
 
 type userInterface struct{}
 
@@ -161,55 +161,55 @@ func Init() {
 	canvas.Get("style").Set("outline", "none")
 
 	// Keyboard
-	canvas.Call("addEventListener", "keydown", func(e js.Object) {
+	canvas.Call("addEventListener", "keydown", func(e *js.Object) {
 		e.Call("preventDefault")
 		code := e.Get("keyCode").Int()
 		currentInput.KeyDown(code)
 	})
-	canvas.Call("addEventListener", "keyup", func(e js.Object) {
+	canvas.Call("addEventListener", "keyup", func(e *js.Object) {
 		e.Call("preventDefault")
 		code := e.Get("keyCode").Int()
 		currentInput.KeyUp(code)
 	})
 
 	// Mouse
-	canvas.Call("addEventListener", "mousedown", func(e js.Object) {
+	canvas.Call("addEventListener", "mousedown", func(e *js.Object) {
 		e.Call("preventDefault")
 		button := e.Get("button").Int()
 		currentInput.MouseDown(button)
 		setMouseCursorFromEvent(e)
 	})
-	canvas.Call("addEventListener", "mouseup", func(e js.Object) {
+	canvas.Call("addEventListener", "mouseup", func(e *js.Object) {
 		e.Call("preventDefault")
 		button := e.Get("button").Int()
 		currentInput.MouseUp(button)
 		setMouseCursorFromEvent(e)
 	})
-	canvas.Call("addEventListener", "mousemove", func(e js.Object) {
+	canvas.Call("addEventListener", "mousemove", func(e *js.Object) {
 		e.Call("preventDefault")
 		setMouseCursorFromEvent(e)
 	})
-	canvas.Call("addEventListener", "contextmenu", func(e js.Object) {
+	canvas.Call("addEventListener", "contextmenu", func(e *js.Object) {
 		e.Call("preventDefault")
 	})
 
 	// Touch (emulating mouse events)
 	// TODO: Create indimendent touch functions
-	canvas.Call("addEventListener", "touchstart", func(e js.Object) {
+	canvas.Call("addEventListener", "touchstart", func(e *js.Object) {
 		e.Call("preventDefault")
 		currentInput.MouseDown(0)
 		touches := e.Get("changedTouches")
 		touch := touches.Index(0)
 		setMouseCursorFromEvent(touch)
 	})
-	canvas.Call("addEventListener", "touchend", func(e js.Object) {
+	canvas.Call("addEventListener", "touchend", func(e *js.Object) {
 		e.Call("preventDefault")
 		currentInput.MouseUp(0)
 		touches := e.Get("changedTouches")
 		touch := touches.Index(0)
 		setMouseCursorFromEvent(touch)
 	})
-	canvas.Call("addEventListener", "touchmove", func(e js.Object) {
+	canvas.Call("addEventListener", "touchmove", func(e *js.Object) {
 		e.Call("preventDefault")
 		touches := e.Get("changedTouches")
 		touch := touches.Index(0)
@@ -217,12 +217,12 @@ func Init() {
 	})
 
 	// Gamepad
-	window.Call("addEventListener", "gamepadconnected", func(e js.Object) {
+	window.Call("addEventListener", "gamepadconnected", func(e *js.Object) {
 		// Do nothing.
 	})
 }
 
-func setMouseCursorFromEvent(e js.Object) {
+func setMouseCursorFromEvent(e *js.Object) {
 	scale := canvas.Get("dataset").Get("ebitenScale").Int()
 	rect := canvas.Call("getBoundingClientRect")
 	x, y := e.Get("clientX").Int(), e.Get("clientY").Int()