diff --git a/cmd/go.mod b/cmd/go.mod
index 401f45e9..737eabe0 100644
--- a/cmd/go.mod
+++ b/cmd/go.mod
@@ -3,6 +3,8 @@ module gioui.org/cmd
 go 1.13
 
 require (
+	gioui.org/ui v0.0.0-20190922141907-2d8072fbbbc6
+	github.com/chromedp/chromedp v0.4.0
 	golang.org/x/image v0.0.0-20190802002840-cff245a6509b
 	golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4
 )
diff --git a/cmd/go.sum b/cmd/go.sum
index fed120b4..31bb2db4 100644
--- a/cmd/go.sum
+++ b/cmd/go.sum
@@ -1,5 +1,24 @@
+gioui.org/ui v0.0.0-20190922141907-2d8072fbbbc6 h1:zK+bNIQHKtFYsK8WjI3A+mChXOoHpQbmSzTXFvZg+2o=
+gioui.org/ui v0.0.0-20190922141907-2d8072fbbbc6/go.mod h1:PssKPKlqVIeyaed+0w492Xc2NgX5M3n6oZKOAj5rxoE=
+github.com/chromedp/cdproto v0.0.0-20190812224334-39ef923dcb8d h1:00kLGv5nKzpFchNhGDXDRbKtYx/WoT983Ka2t8/pzRE=
+github.com/chromedp/cdproto v0.0.0-20190812224334-39ef923dcb8d/go.mod h1:0YChpVzuLJC5CPr+x3xkHN6Z8KOSXjNbL7qV8Wc4GW0=
+github.com/chromedp/chromedp v0.4.0 h1:0AJC5ejETuh/6n7Tcsw4u4G0eKZkI9aVRwckWaImLUE=
+github.com/chromedp/chromedp v0.4.0/go.mod h1:DC3QUn4mJ24dwjcaGQLoZrhm4X/uPHZ6spDbS2uFhm4=
+github.com/gobwas/httphead v0.0.0-20180130184737-2c6c146eadee h1:s+21KNqlpePfkah2I+gwHF8xmJWRjooY+5248k6m4A0=
+github.com/gobwas/httphead v0.0.0-20180130184737-2c6c146eadee/go.mod h1:L0fX3K22YWvt/FAX9NnzrNzcI4wNYi9Yku4O0LKYflo=
+github.com/gobwas/pool v0.2.0 h1:QEmUOlnSjWtnpRGHF3SauEiOsy82Cup83Vf2LcMlnc8=
+github.com/gobwas/pool v0.2.0/go.mod h1:q8bcK0KcYlCgd9e7WYLm9LpyS+YeLd8JVDW6WezmKEw=
+github.com/gobwas/ws v1.0.2 h1:CoAavW/wd/kulfZmSIBt6p24n4j7tHgNVCjsfHVNUbo=
+github.com/gobwas/ws v1.0.2/go.mod h1:szmBTxLgaFppYjEmNtny/v3w89xOydFnnZMcgRRu/EM=
+github.com/knq/sysutil v0.0.0-20181215143952-f05b59f0f307 h1:vl4eIlySbjertFaNwiMjXsGrFVK25aOWLq7n+3gh2ls=
+github.com/knq/sysutil v0.0.0-20181215143952-f05b59f0f307/go.mod h1:BjPj+aVjl9FW/cCGiF3nGh5v+9Gd3VCgBQbod/GlMaQ=
+github.com/mailru/easyjson v0.0.0-20190626092158-b2ccc519800e h1:hB2xlXdHp/pmPZq0y3QnmWAArdw9PqbmotexnWx/FU8=
+github.com/mailru/easyjson v0.0.0-20190626092158-b2ccc519800e/go.mod h1:C1wdFJiN94OJF2b5HbByQZoLdCWB1Yqtg26g4irojpc=
+golang.org/x/image v0.0.0-20190703141733-d6a02ce849c9/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/image v0.0.0-20190802002840-cff245a6509b h1:+qEpEAPhDZ1o0x3tHzZTQDArnOixOzGD9HUJfcg0mb4=
 golang.org/x/image v0.0.0-20190802002840-cff245a6509b/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4 h1:YUO/7uOKsKeq9UokNS62b8FYywz3ker1l1vDZRCRefw=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190813064441-fde4db37ae7a h1:aYOabOQFp6Vj6W1F80affTUvO9UxmJRx8K0gsfABByQ=
+golang.org/x/sys v0.0.0-20190813064441-fde4db37ae7a/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
diff --git a/cmd/gogio/js_test.go b/cmd/gogio/js_test.go
new file mode 100644
index 00000000..9241891b
--- /dev/null
+++ b/cmd/gogio/js_test.go
@@ -0,0 +1,104 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package main_test
+
+import (
+	"bytes"
+	"context"
+	"image/png"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"os/exec"
+	"testing"
+
+	"github.com/chromedp/chromedp"
+
+	_ "gioui.org/ui" // the build tool adds it to go.mod, so keep it there
+)
+
+func TestJSOnChrome(t *testing.T) {
+	// First, build the app.
+	dir, err := ioutil.TempDir("", "gio-endtoend-js")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(dir)
+
+	// TODO(mvdan): This is inefficient, as we link the gogio tool every time.
+	// Consider options in the future. On the plus side, this is simple.
+	cmd := exec.Command("go", "run", ".", "-target=js", "-o="+dir, "testdata/red.go")
+	if out, err := cmd.CombinedOutput(); err != nil {
+		t.Fatalf("could not build app: %s:\n%s", err, out)
+	}
+
+	// Second, start Chrome.
+	opts := append(chromedp.DefaultExecAllocatorOptions[:],
+		// Uncomment to get the browser's GUI.
+		// chromedp.Flag("headless", false),
+		// We need use-gl=egl instead of the default of use-gl=desktop;
+		// "desktop" doesn't seem to work when we're in headless mode.
+		// TODO(mvdan): Does egl require a GPU? If so, consider
+		// use-gl=swiftshader, which will use CPU-based rendering. That
+		// might be necessary for some CI or headless environments.
+		chromedp.Flag("use-gl", "egl"),
+	)
+
+	actx, cancel := chromedp.NewExecAllocator(context.Background(), opts...)
+	defer cancel()
+
+	ctx, cancel := chromedp.NewContext(actx)
+	defer cancel()
+
+	if err := chromedp.Run(ctx); err != nil {
+		// TODO(mvdan): Skip the test if chrome/chromium/headless-shell
+		// aren't installed.
+		t.Fatal(err)
+	}
+
+	// Third, serve the app folder, set the browser tab dimensions, and
+	// navigate to the folder.
+	ts := httptest.NewServer(http.FileServer(http.Dir(dir)))
+	defer ts.Close()
+
+	if err := chromedp.Run(ctx,
+		// A small window with 2x HiDPI.
+		chromedp.EmulateViewport(300, 300, chromedp.EmulateScale(2.0)),
+		chromedp.Navigate(ts.URL),
+	); err != nil {
+		t.Fatal(err)
+	}
+
+	// Finally, run the test.
+
+	// 1: Once the canvas is ready, grab a screenshot to check that the
+	//    entirety of the viewport is red, as per the background color.
+	var buf []byte
+	if err := chromedp.Run(ctx,
+		chromedp.WaitReady("canvas", chromedp.ByQuery),
+		chromedp.CaptureScreenshot(&buf),
+	); err != nil {
+		t.Fatal(err)
+	}
+	img, err := png.Decode(bytes.NewReader(buf))
+	if err != nil {
+		t.Fatal(err)
+	}
+	size := img.Bounds().Size()
+	wantSize := 600 // 300px at 2.0 scaling factor
+	if size.X != wantSize || size.Y != wantSize {
+		t.Fatalf("expected dimensions to be %d*%d, got %d*%d",
+			wantSize, wantSize, size.X, size.Y)
+	}
+	wantColor := func(x, y int, r, g, b, a uint32) {
+		color := img.At(x, y)
+		r_, g_, b_, a_ := color.RGBA()
+		if r_ != r || g_ != g || b_ != b || a_ != a {
+			t.Errorf("got 0x%04x%04x%04x%04x at (%d,%d), want 0x%04x%04x%04x%04x",
+				r_, g_, b_, a_, x, y, r, g, b, a)
+		}
+	}
+	wantColor(5, 5, 0xffff, 0x0, 0x0, 0xffff)
+	wantColor(595, 595, 0xffff, 0x0, 0x0, 0xffff)
+}
diff --git a/cmd/gogio/testdata/red.go b/cmd/gogio/testdata/red.go
new file mode 100644
index 00000000..0de41e65
--- /dev/null
+++ b/cmd/gogio/testdata/red.go
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+// A dead simple app that just paints the background red.
+package main
+
+import (
+	"image/color"
+	"log"
+
+	"gioui.org/ui"
+	"gioui.org/ui/app"
+	"gioui.org/ui/f32"
+	"gioui.org/ui/paint"
+)
+
+func main() {
+	go func() {
+		w := app.NewWindow()
+		if err := loop(w); err != nil {
+			log.Fatal(err)
+		}
+	}()
+	app.Main()
+}
+
+func loop(w *app.Window) error {
+	background := color.RGBA{255, 0, 0, 255}
+	ops := new(ui.Ops)
+	for {
+		e := <-w.Events()
+		switch e := e.(type) {
+		case app.DestroyEvent:
+			return e.Err
+		case app.UpdateEvent:
+			ops.Reset()
+			paint.ColorOp{Color: background}.Add(ops)
+			paint.PaintOp{Rect: f32.Rectangle{Max: f32.Point{
+				X: float32(e.Size.X),
+				Y: float32(e.Size.Y),
+			}}}.Add(ops)
+			w.Update(ops)
+		}
+	}
+}