Editor: Clean GPL implementation of tabindex

client/components/tinymce/index.jsx

@@ -32,7 +32,7 @@ require( './plugins/wpeditimage/plugin.js' )();
 require( './plugins/wplink/plugin.js' )();
 require( './plugins/media/plugin' )();
 require( './plugins/advanced/plugin' )();
-require( './plugins/tabindex/plugin' )();
+require( './plugins/wpcom-tabindex/plugin' )();
 require( './plugins/touch-scroll-toolbar/plugin' )();
 require( './plugins/editor-button-analytics/plugin' )();
 require( './plugins/calypso-alert/plugin' )();
@@ -89,6 +89,7 @@ const PLUGINS = [
 	'wpcom/advanced',
 	'wpcom/help',
 	'wpcom/charmap',
+	'wpcom/tabindex',
 	'wpcom/touchscrolltoolbar',
 	'wpcom/view',
 	'wpcom/editorbuttonanalytics',

client/components/tinymce/plugins/wpcom-tabindex/plugin.js

@@ -0,0 +1,39 @@
+/**
+ * External dependencies
+ */
+import tinymce from 'tinymce/tinymce';
+
+// Returns a function that sets the tabindex on an editor instance.
+// The returned function assumes that `this` is set to the editor instance
+function setTabIndexOnEditorIframe( tabindex ) {
+	return function() {
+		// At this point, there's an iframe in the DOM with the id of `${editor.id}_ifr`.
+		// Can't find a way to get at it without hopping out to the DOM :/
+		const editorIframe = document.getElementById( `${this.id}_ifr` );
+
+		if ( ! editorIframe ) {
+			return;
+		}
+
+		editorIframe.setAttribute( 'tabIndex', tabindex );
+	}
+}
+
+function wpcomTabIndexPlugin( editor ) {
+	const settings = editor && editor.settings;
+
+	if ( ! settings || ! ( 'tabindex' in settings ) ) {
+		return;
+	}
+
+	const tabindex = Math.min( 32767, Number( settings.tabindex ) );
+	if ( ! Number.isInteger( tabindex ) ) {
+		return;
+	}
+
+	editor.on( 'init', setTabIndexOnEditorIframe( tabindex ) );
+}
+
+export default function() {
+	tinymce.PluginManager.add( 'wpcom/tabindex', wpcomTabIndexPlugin );
+};