Configure document-title during updates

CHANGELOG.md

@@ -2,6 +2,10 @@
 All notable changes to `dash` will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
+## Unreleased
+### Added
+- [#1315](https://github.com/plotly/dash/pull/1315) Add `update_title` parameter to set or disable the "Updating...." document title during updates. Closes [#856](https://github.com/plotly/dash/issues/856) and [#732](https://github.com/plotly/dash/issues/732)
+
 ## [1.13.4] - 2020-06-25 
 ### Fixed
 - [#1310](https://github.com/plotly/dash/pull/1310) Fix a regression since 1.13.0 preventing more than one loading state from being shown at a time.

dash-renderer/src/components/core/DocumentTitle.react.js

@@ -5,14 +5,16 @@ import PropTypes from 'prop-types';
 class DocumentTitle extends Component {
     constructor(props) {
         super(props);
+        const {update_title} = props.config;
         this.state = {
             initialTitle: document.title,
+            update_title,
         };
     }
 
     UNSAFE_componentWillReceiveProps(props) {
-        if (props.isLoading) {
-            document.title = 'Updating...';
+        if (this.state.update_title && props.isLoading) {
+            document.title = this.state.update_title;
         } else {
             document.title = this.state.initialTitle;
         }
@@ -29,8 +31,10 @@ class DocumentTitle extends Component {
 
 DocumentTitle.propTypes = {
     isLoading: PropTypes.bool.isRequired,
+    config: PropTypes.shape({update_title: PropTypes.string}),
 };
 
 export default connect(state => ({
     isLoading: state.isLoading,
+    config: state.config,
 }))(DocumentTitle);

dash/dash.py

@@ -252,6 +252,7 @@ def __init__(
         prevent_initial_callbacks=False,
         show_undo_redo=False,
         plugins=None,
+        update_title="Updating...",
         **obsolete
     ):
         _validate.check_obsolete(obsolete)
@@ -299,6 +300,7 @@ def __init__(
             ),
             prevent_initial_callbacks=prevent_initial_callbacks,
             show_undo_redo=show_undo_redo,
+            update_title=update_title,
         )
         self.config.set_read_only(
             [
@@ -506,6 +508,7 @@ def _config(self):
             "props_check": self._dev_tools.props_check,
             "show_undo_redo": self.config.show_undo_redo,
             "suppress_callback_exceptions": self.config.suppress_callback_exceptions,
+            "update_title": self.config.update_title,
         }
         if self._dev_tools.hot_reload:
             config["hot_reload"] = {

tests/integration/renderer/test_loading_states.py

@@ -1,7 +1,9 @@
 from multiprocessing import Lock
 
+import pytest
 import dash
 from dash.dependencies import Input, Output
+from dash.testing.wait import until
 
 import dash_core_components as dcc
 import dash_html_components as html
@@ -167,3 +169,46 @@ def find_text(spec):
 
     find_spinners()
     find_text({1: 1, 2: 1, 3: 1, 4: 1})
+
+
+@pytest.mark.parametrize(
+    "kwargs, expected_update_title",
+    [
+        ({}, "Updating..."),
+        ({"update_title": None}, "Dash"),
+        ({"update_title": ""}, "Dash"),
+        ({"update_title": "Hello World"}, "Hello World"),
+    ]
+)
+def test_rdls003_update_title(dash_duo, kwargs, expected_update_title):
+    app = dash.Dash("Dash", **kwargs)
+    lock = Lock()
+
+    app.layout = html.Div(
+        children=[
+            html.H3("Press button see document title updating"),
+            html.Div(id="output"),
+            html.Button("Update", id="button", n_clicks=0),
+        ]
+    )
+
+    @app.callback(
+        Output("output", "children"),
+        [Input("button", "n_clicks")]
+    )
+    def update(n):
+        with lock:
+            # check for update-title while processing callback
+            until(lambda: dash_duo.driver.title == expected_update_title, timeout=1)
+        return n
+
+    with lock:
+        dash_duo.start_server(app)
+        # check for update-title on load
+        until(lambda: dash_duo.driver.title == expected_update_title, timeout=1)
+
+    # check for original title after loading
+    until(lambda: dash_duo.driver.title == "Dash", timeout=1)
+
+    with lock:
+        dash_duo.find_element("#button").click()