From bd84c5806e46e4eb83b39cee74db085504ca9a0e Mon Sep 17 00:00:00 2001
From: Thomas Kluyver <thomas@kluyver.me.uk>
Date: Thu, 27 Jul 2017 14:16:53 +0100
Subject: [PATCH] Validate CodeMirror keyMap from frontend config

Closes gh-1976
---
 notebook/static/notebook/js/notebook.js | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/notebook/static/notebook/js/notebook.js b/notebook/static/notebook/js/notebook.js
index c051d62f6..0ae246db9 100644
--- a/notebook/static/notebook/js/notebook.js
+++ b/notebook/static/notebook/js/notebook.js
@@ -87,6 +87,7 @@ define([
      */
     function Notebook(selector, options) {
         this.config = options.config;
+        this.config.loaded.then(this.validate_config.bind(this))
         this.class_config = new configmod.ConfigWithDefaults(this.config, 
                                         Notebook.options_default, 'Notebook');
         this.base_url = options.base_url;
@@ -259,6 +260,15 @@ define([
         Toolbar: true
     };
 
+    Notebook.prototype.validate_config = function() {
+        var code_cell = this.config.data['CodeCell'] || {};
+        var cm_keymap = (code_cell['cm_config'] || {})['keyMap'];
+        if (cm_keymap && CodeMirror.keyMap[cm_keymap] === undefined) {
+            console.warn('CodeMirror keymap not found, ignoring: ' + cm_keymap);
+            delete code_cell.cm_config.keyMap;
+        }
+    };
+
     /**
      * Create an HTML and CSS representation of the notebook.
      */