Teach <cxx-section> to check for an id, and document the checkInvariants() function.

jyasskin · jyasskin · commit 23c55aa6eec3 · 2014-02-28T23:14:01.000-08:00
diff --git a/README.md b/README.md
@@ -19,6 +19,13 @@ Contributor License Agreement at https://developers.google.com/open-source/cla/i
 Custom C++-specific elements
 ----------------------------
 
+Some of these elements define a `checkInvariants()` method, so you can run:
+
+    document.querySelectorAll('*').array().forEach(
+        function(node){ if (node.checkInvariants) node.checkInvariants(); });
+
+to see if you've gotten anything wrong.
+
 ### `<cxx-include href="other.html">`
 
 This one isn't really C++-specific: it allows partitioning a main document
diff --git a/section.js b/section.js
@@ -20,6 +20,12 @@ limitations under the License.
 
         applyAuthorStyles: true,
 
+        checkInvariants: function() {
+            if (!this.id) {
+                console.error(this, 'is missing an id.');
+            }
+        },
+
         update_sec_nums: function(sec_num) {
             this.sec_num = sec_num + '';
             var child_index = 1;
