Merge pull request #2034 from adrianoesch/patch-1

New dcc.Markdown prop 'link_target'

Author: alexcjohnson

Diff for: CHANGELOG.md

@@ -16,6 +16,8 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 
 - [#1956](https://github.com/plotly/dash/pull/1956) Add TypeScript components generation.
 
+- [#2034](https://github.com/plotly/dash/pull/2034) Add `link_target` prop to dcc.Markdown component. Closes [#1827](https://github.com/plotly/dash/issues/1827)
+
 ### Fixed
 
 - [#2029](https://github.com/plotly/dash/pull/2029) Restrict the number of props listed explicitly in generated component constructors - default is 250. This prevents exceeding the Python 3.6 limit of 255 arguments. The omitted props are still in the docstring and can still be provided the same as before, they just won't appear in the signature so autocompletion may be affected.

Diff for: components/dash-core-components/src/components/Markdown.react.js

@@ -53,6 +53,11 @@ DashMarkdown.propTypes = {
      */
     dangerously_allow_html: PropTypes.bool,
 
+    /**
+     * A string for the target attribute to use on links (such as "_blank")
+     */
+    link_target: PropTypes.string,
+
     /**
      * A markdown string (or array of strings) that adhreres to the CommonMark spec
      */

Diff for: components/dash-core-components/src/fragments/Markdown.react.js

@@ -87,6 +87,7 @@ export default class DashMarkdown extends Component {
             highlight_config,
             loading_state,
             dangerously_allow_html,
+            link_target,
             mathjax,
             children,
             dedent,
@@ -134,6 +135,7 @@ export default class DashMarkdown extends Component {
                 <Markdown
                     source={displayText}
                     escapeHtml={!dangerously_allow_html}
+                    linkTarget={link_target}
                     plugins={mathjax ? [RemarkMath] : []}
                     renderers={{
                         math: props => (

Diff for: components/dash-core-components/tests/integration/markdown/test_markdown.py

@@ -1,5 +1,6 @@
 import pytest
 from dash import Dash, dcc, html, Input, Output
+from dash.testing.wait import until
 
 
 def test_mkdw001_img(dash_dcc):
@@ -374,3 +375,16 @@ def test_mkdw008_mathjax_visual(dash_dcc):
     dash_dcc.percy_snapshot("mkdw008 - markdown and graph with/without mathjax")
 
     assert dash_dcc.get_logs() == []
+
+
+def test_mkdw009_target_blank_links(dash_dcc):
+
+    app = Dash(__name__)
+
+    app.layout = dcc.Markdown("[link](https://duckduckgo.com)", link_target="_blank")
+
+    dash_dcc.start_server(app)
+
+    dash_dcc.find_element("a").click()
+
+    until(lambda: len(dash_dcc.driver.window_handles) == 2, timeout=1)