diff --git a/cmd/query/app/fixture/index.html b/cmd/query/app/fixture/index.html
index 1fa312504ce..0bce65817e0 100644
--- a/cmd/query/app/fixture/index.html
+++ b/cmd/query/app/fixture/index.html
@@ -3,6 +3,10 @@
     <meta charset="UTF-8">
     <base href="/" data-inject-target="BASE_URL"/>
     <title>Test Page</title>
-    <!-- JAEGER_CONFIG=DEFAULT_CONFIG; -->
-    <!-- JAEGER_VERSION=DEFAULT_VERSION; -->
+    <!--
+        // JAEGER_CONFIG_JS
+        // the line above may be replaced by user-provided JS file that should define a UIConfig function.
+        JAEGER_CONFIG=DEFAULT_CONFIG;
+        JAEGER_VERSION=DEFAULT_VERSION;
+    -->
 </html>
diff --git a/cmd/query/app/fixture/ui-config-malformed.js b/cmd/query/app/fixture/ui-config-malformed.js
new file mode 100644
index 00000000000..1956f1b31e6
--- /dev/null
+++ b/cmd/query/app/fixture/ui-config-malformed.js
@@ -0,0 +1,10 @@
+() => {
+  return {
+    menu: [
+      {
+        label: "GitHub",
+        url: "https://github.com/jaegertracing/jaeger"
+      }
+    ]
+  }
+}
diff --git a/cmd/query/app/fixture/ui-config-menu.js b/cmd/query/app/fixture/ui-config-menu.js
new file mode 100644
index 00000000000..74863a63ee4
--- /dev/null
+++ b/cmd/query/app/fixture/ui-config-menu.js
@@ -0,0 +1,10 @@
+function UIConfig(){
+  return {
+    menu: [
+      {
+        label: "GitHub",
+        url: "https://github.com/jaegertracing/jaeger"
+      }
+    ]
+  }
+}
diff --git a/cmd/query/app/fixture/ui-config.js b/cmd/query/app/fixture/ui-config.js
new file mode 100644
index 00000000000..edd2a0bfcd8
--- /dev/null
+++ b/cmd/query/app/fixture/ui-config.js
@@ -0,0 +1,5 @@
+function UIConfig(){
+  return {
+    x: "y"
+  }
+}
diff --git a/cmd/query/app/static_handler.go b/cmd/query/app/static_handler.go
index bf8632c1859..e60a451b979 100644
--- a/cmd/query/app/static_handler.go
+++ b/cmd/query/app/static_handler.go
@@ -16,6 +16,7 @@
 package app
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
@@ -40,6 +41,7 @@ var (
 
 	// The following patterns are searched and replaced in the index.html as a way of customizing the UI.
 	configPattern   = regexp.MustCompile("JAEGER_CONFIG *= *DEFAULT_CONFIG;")
+	configJsPattern = regexp.MustCompile(`(?im)^\s*\/\/\s*JAEGER_CONFIG_JS.*\n.*`)
 	versionPattern  = regexp.MustCompile("JAEGER_VERSION *= *DEFAULT_VERSION;")
 	basePathPattern = regexp.MustCompile(`<base href="/"`) // Note: tag is not closed
 )
@@ -75,6 +77,11 @@ type StaticAssetsHandlerOptions struct {
 	NewWatcher   func() (fswatcher.Watcher, error)
 }
 
+type loadedConfig struct {
+	regexp *regexp.Regexp
+	config []byte
+}
+
 // NewStaticAssetsHandler returns a StaticAssetsHandler
 func NewStaticAssetsHandler(staticAssetsRoot string, options StaticAssetsHandlerOptions) (*StaticAssetsHandler, error) {
 	assetsFS := ui.StaticFiles
@@ -113,17 +120,11 @@ func loadAndEnrichIndexHTML(open func(string) (http.File, error), options Static
 		return nil, fmt.Errorf("cannot load index.html: %w", err)
 	}
 	// replace UI config
-	configString := "JAEGER_CONFIG = DEFAULT_CONFIG"
-	if config, err := loadUIConfig(options.UIConfigPath); err != nil {
+	if configObject, err := loadUIConfig(options.UIConfigPath); err != nil {
 		return nil, err
-	} else if config != nil {
-		// TODO if we want to support other config formats like YAML, we need to normalize `config` to be
-		// suitable for json.Marshal(). For example, YAML parser may return a map that has keys of type
-		// interface{}, and json.Marshal() is unable to serialize it.
-		bytes, _ := json.Marshal(config)
-		configString = fmt.Sprintf("JAEGER_CONFIG = %v", string(bytes))
+	} else if configObject != nil {
+		indexBytes = configObject.regexp.ReplaceAll(indexBytes, configObject.config)
 	}
-	indexBytes = configPattern.ReplaceAll(indexBytes, []byte(configString+";"))
 	// replace Jaeger version
 	versionJSON, _ := json.Marshal(version.Get())
 	versionString := fmt.Sprintf("JAEGER_VERSION = %s;", string(versionJSON))
@@ -218,30 +219,44 @@ func loadIndexHTML(open func(string) (http.File, error)) ([]byte, error) {
 	return indexBytes, nil
 }
 
-func loadUIConfig(uiConfig string) (map[string]interface{}, error) {
+func loadUIConfig(uiConfig string) (*loadedConfig, error) {
 	if uiConfig == "" {
 		return nil, nil
 	}
-	ext := filepath.Ext(uiConfig)
-	bytes, err := ioutil.ReadFile(filepath.Clean(uiConfig))
+	bytesConfig, err := ioutil.ReadFile(filepath.Clean(uiConfig))
 	if err != nil {
 		return nil, fmt.Errorf("cannot read UI config file %v: %w", uiConfig, err)
 	}
+	var r []byte
 
-	var c map[string]interface{}
-	var unmarshal func([]byte, interface{}) error
-
+	ext := filepath.Ext(uiConfig)
 	switch strings.ToLower(ext) {
 	case ".json":
-		unmarshal = json.Unmarshal
-	default:
-		return nil, fmt.Errorf("unrecognized UI config file format %v", uiConfig)
-	}
+		var c map[string]interface{}
 
-	if err := unmarshal(bytes, &c); err != nil {
-		return nil, fmt.Errorf("cannot parse UI config file %v: %w", uiConfig, err)
+		if err := json.Unmarshal(bytesConfig, &c); err != nil {
+			return nil, fmt.Errorf("cannot parse UI config file %v: %w", uiConfig, err)
+		}
+		r, _ = json.Marshal(c)
+
+		return &loadedConfig{
+			regexp: configPattern,
+			config: append([]byte("JAEGER_CONFIG = "), append(r, byte(';'))...),
+		}, nil
+	case ".js":
+		r = bytes.TrimSpace(bytesConfig)
+		re := regexp.MustCompile(`function\s+UIConfig(\s)?\(\s?\)(\s)?{`)
+		if !re.Match(r) {
+			return nil, fmt.Errorf("UI config file must define function UIConfig(): %v", uiConfig)
+		}
+
+		return &loadedConfig{
+			regexp: configJsPattern,
+			config: r,
+		}, nil
+	default:
+		return nil, fmt.Errorf("unrecognized UI config file format, expecting .js or .json file: %v", uiConfig)
 	}
-	return c, nil
 }
 
 // RegisterRoutes registers routes for this handler on the given router
diff --git a/cmd/query/app/static_handler_test.go b/cmd/query/app/static_handler_test.go
index 0e047fea9c4..348f1e7c5de 100644
--- a/cmd/query/app/static_handler_test.go
+++ b/cmd/query/app/static_handler_test.go
@@ -16,6 +16,7 @@
 package app
 
 import (
+	"encoding/json"
 	"fmt"
 	"io/ioutil"
 	"net/http"
@@ -63,10 +64,31 @@ func TestRegisterStaticHandler(t *testing.T) {
 		subroute         bool   // should we create a subroute?
 		baseURL          string // expected URL prefix
 		expectedBaseHTML string // substring to match in the home page
+		UIConfigPath     string // path to UI config
+		expectedUIConfig string // expected UI config
 	}{
-		{basePath: "", baseURL: "/", expectedBaseHTML: `<base href="/"`},
-		{basePath: "/", baseURL: "/", expectedBaseHTML: `<base href="/"`},
-		{basePath: "/jaeger", baseURL: "/jaeger/", expectedBaseHTML: `<base href="/jaeger/"`, subroute: true},
+		{
+			basePath:         "",
+			baseURL:          "/",
+			expectedBaseHTML: `<base href="/"`,
+			UIConfigPath:     "",
+			expectedUIConfig: "JAEGER_CONFIG=DEFAULT_CONFIG;",
+		},
+		{
+			basePath:         "/",
+			baseURL:          "/",
+			expectedBaseHTML: `<base href="/"`,
+			UIConfigPath:     "fixture/ui-config.json",
+			expectedUIConfig: `JAEGER_CONFIG = {"x":"y"};`,
+		},
+		{
+			basePath:         "/jaeger",
+			baseURL:          "/jaeger/",
+			expectedBaseHTML: `<base href="/jaeger/"`,
+			subroute:         true,
+			UIConfigPath:     "fixture/ui-config.js",
+			expectedUIConfig: "function UIConfig(){",
+		},
 	}
 	httpClient = &http.Client{
 		Timeout: 2 * time.Second,
@@ -81,7 +103,7 @@ func TestRegisterStaticHandler(t *testing.T) {
 			RegisterStaticHandler(r, logger, &QueryOptions{
 				StaticAssets: "fixture",
 				BasePath:     testCase.basePath,
-				UIConfig:     "fixture/ui-config.json",
+				UIConfig:     testCase.UIConfigPath,
 			})
 
 			server := httptest.NewServer(r)
@@ -103,7 +125,7 @@ func TestRegisterStaticHandler(t *testing.T) {
 			assert.Contains(t, respString, "Test Favicon") // this text is present in fixtures/favicon.ico
 
 			html := httpGet("") // get home page
-			assert.Contains(t, html, `JAEGER_CONFIG = {"x":"y"};`, "actual: %v", html)
+			assert.Contains(t, html, testCase.expectedUIConfig, "actual: %v", html)
 			assert.Contains(t, html, `JAEGER_VERSION = {"gitCommit":"","gitVersion":"","buildDate":""};`, "actual: %v", html)
 			assert.Contains(t, html, testCase.expectedBaseHTML, "actual: %v", html)
 
@@ -260,7 +282,7 @@ func TestHotReloadUIConfigTempFile(t *testing.T) {
 func TestLoadUIConfig(t *testing.T) {
 	type testCase struct {
 		configFile    string
-		expected      map[string]interface{}
+		expected      *loadedConfig
 		expectedError string
 	}
 
@@ -277,13 +299,13 @@ func TestLoadUIConfig(t *testing.T) {
 	}
 
 	run("no config", testCase{})
-	run("invalid config", testCase{
+	run("invalid json config", testCase{
 		configFile:    "invalid",
 		expectedError: "cannot read UI config file invalid: open invalid: no such file or directory",
 	})
 	run("unsupported type", testCase{
 		configFile:    "fixture/ui-config.toml",
-		expectedError: "unrecognized UI config file format fixture/ui-config.toml",
+		expectedError: "unrecognized UI config file format, expecting .js or .json file: fixture/ui-config.toml",
 	})
 	run("malformed", testCase{
 		configFile:    "fixture/ui-config-malformed.json",
@@ -291,19 +313,55 @@ func TestLoadUIConfig(t *testing.T) {
 	})
 	run("json", testCase{
 		configFile: "fixture/ui-config.json",
-		expected:   map[string]interface{}{"x": "y"},
+		expected: &loadedConfig{
+			config: []byte(`JAEGER_CONFIG = {"x":"y"};`),
+			regexp: configPattern,
+		},
+	})
+	c, _ := json.Marshal(map[string]interface{}{
+		"menu": []interface{}{
+			map[string]interface{}{
+				"label": "GitHub",
+				"url":   "https://github.com/jaegertracing/jaeger",
+			},
+		},
 	})
 	run("json-menu", testCase{
 		configFile: "fixture/ui-config-menu.json",
-		expected: map[string]interface{}{
-			"menu": []interface{}{
-				map[string]interface{}{
-					"label": "GitHub",
-					"url":   "https://github.com/jaegertracing/jaeger",
-				},
-			},
+		expected: &loadedConfig{
+			config: append([]byte("JAEGER_CONFIG = "), append(c, byte(';'))...),
+			regexp: configPattern,
 		},
 	})
+	run("malformed js config", testCase{
+		configFile:    "fixture/ui-config-malformed.js",
+		expectedError: "UI config file must define function UIConfig(): fixture/ui-config-malformed.js",
+	})
+	run("js", testCase{
+		configFile: "fixture/ui-config.js",
+		expected: &loadedConfig{
+			regexp: configJsPattern,
+			config: []byte(`function UIConfig(){
+  return {
+    x: "y"
+  }
+}`)},
+	})
+	run("js-menu", testCase{
+		configFile: "fixture/ui-config-menu.js",
+		expected: &loadedConfig{
+			regexp: configJsPattern,
+			config: []byte(`function UIConfig(){
+  return {
+    menu: [
+      {
+        label: "GitHub",
+        url: "https://github.com/jaegertracing/jaeger"
+      }
+    ]
+  }
+}`)},
+	})
 }
 
 type fakeFile struct {
diff --git a/jaeger-ui b/jaeger-ui
index 1d0330d6519..1c9a9bada12 160000
--- a/jaeger-ui
+++ b/jaeger-ui
@@ -1 +1 @@
-Subproject commit 1d0330d6519316037109dbafc4afd9c5123779c9
+Subproject commit 1c9a9bada1249b4a51e0a708160dbdca76eff89a