From c8992fa4216f2c81df0dfbcdee1ff7edb09a16ef Mon Sep 17 00:00:00 2001
From: Nikhil Dabas <nikhil@nikhildabas.com>
Date: Wed, 10 Aug 2016 14:42:34 +0530
Subject: [PATCH] Release 0.4.0

Update automatic ID generation to support int'l character sets, and
prevent duplicate IDs.
---
 README.md       |  9 ++++-----
 bower.json      |  2 +-
 docs/index.html | 12 ++++++------
 jquery.toc.js   | 32 ++++++++++++++++++++++++++------
 package.json    |  2 +-
 toc.jquery.json |  2 +-
 6 files changed, 39 insertions(+), 20 deletions(-)

diff --git a/README.md b/README.md
index 80d92df..c935694 100644
--- a/README.md
+++ b/README.md
@@ -69,12 +69,11 @@ assigned; if they do not, the plugin will generate and assign IDs automatically.
 
 The generated IDs are based on the text inside the headings, and uses two simple rules:
 
-* The ID must begin with a letter; so any non-letter (`[^A-Za-z]`) characters are discarded from the
-  beginning of the string.
-* For the rest of the ID, only letters and numbers are used from the heading text; all other
-  characters (`[^A-Za-z0-9]`) are converted to underscores.
+* Space characters are converted to underscores. Multiple spaces are replaced with a single
+  underscore.
+* If the ID already exists, a suffix like "_1", "_2", etc. is tried till we get a unique ID.
 
-For example, a heading like `<h2>Heading 2.1</h2>` will get the ID `Heading_2_1`.
+For example, a heading like `<h2>Heading 2.1</h2>` will get the ID `Heading_2.1`.
 
 ## Alternatives
 
diff --git a/bower.json b/bower.json
index 9d72115..6aba7e5 100644
--- a/bower.json
+++ b/bower.json
@@ -1,6 +1,6 @@
 {
     "name": "jquery.toc",
-    "version": "0.3.5",
+    "version": "0.4.0",
     "main": "./jquery.toc.js",
     "dependencies": {
         "jquery": ">=1.6.3"
diff --git a/docs/index.html b/docs/index.html
index fe43e8d..f4ec2fc 100644
--- a/docs/index.html
+++ b/docs/index.html
@@ -12,7 +12,7 @@ <h1>Table of Contents jQuery Plugin</h1>
     <p><a class="btn btn-lg btn-success" href="assets/jquery.toc.zip">Download</a></p>
 
     <p>
-        <span class="muted">Version 0.3.5</span> &middot;
+        <span class="muted">Version 0.4.0</span> &middot;
         <a href="http://github.com/ndabas/toc">GitHub Project</a></p>
 </div>
 
@@ -103,15 +103,15 @@ <h3>Automatic ID generation</h3>
 
     <ul>
         <li>
-            The ID must begin with a letter; so any non-letter (<code>[^A-Za-z]</code>) characters
-            are discarded from the beginning of the string.</li>
-        <li>For the rest of the ID, only letters and numbers are used from the heading text; all
-            other characters (<code>[^A-Za-z0-9]</code>) are converted to underscores.</li>
+            Space characters are converted to underscores. Multiple spaces are replaced with a
+            single underscore.</li>
+        <li>If the ID already exists, a suffix like "_1", "_2", etc. is tried till we get a unique
+            ID.</li>
     </ul>
 
     <p>
         For example, a heading like <code>&lt;h2&gt;Heading 2.1&lt;/h2&gt;</code> will get the ID
-        <code>Heading_2_1</code>.</p>
+        <code>Heading_2.1</code>.</p>
 
     <h2>Alternatives</h2>
 
diff --git a/jquery.toc.js b/jquery.toc.js
index 035c42b..5d6333d 100644
--- a/jquery.toc.js
+++ b/jquery.toc.js
@@ -1,8 +1,8 @@
 /*
  * Table of Contents jQuery Plugin - jquery.toc
  *
- * Copyright 2013 Nikhil Dabas
- * 
+ * Copyright 2013-2016 Nikhil Dabas
+ *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License.  You may obtain a copy of the License at
  *
@@ -42,10 +42,30 @@
 
             // Set up some automatic IDs if we do not already have them
             $(thisOptions.content).find(thisOptions.headings).attr("id", function (index, attr) {
-                // Generate a valid ID: must start with a letter, and contain only letters and
-                // numbers. All other characters are replaced with underscores.
-                return attr ||
-                    $(this).text().replace(/^[^A-Za-z]*/, "").replace(/[^A-Za-z0-9]+/g, "_");
+                // In HTML5, the id attribute must be at least one character long and must not
+                // contain any space characters.
+                //
+				// We just use the HTML5 spec now because all browsers work fine with it.
+                // https://mathiasbynens.be/notes/html5-id-class
+                var generateUniqueId = function (text) {
+                    // Generate a valid ID. Spaces are replaced with underscores. We also check if
+                    // the ID already exists in the document. If so, we append "_1", "_2", etc.
+                    // until we find an unused ID.
+
+                    if (text.length === 0) {
+                        text = "?";
+                    }
+
+                    var baseId = text.replace(/\s+/g, "_"), suffix = "", count = 1;
+
+                    while (document.getElementById(baseId + suffix) !== null) {
+                        suffix = "_" + count++;
+                    }
+
+                    return baseId + suffix;
+                };
+
+                return attr || generateUniqueId($(this).text());
             }).each(function () {
                 // What level is the current heading?
                 var elem = $(this), level = $.map(headingSelectors, function (selector, index) {
diff --git a/package.json b/package.json
index 973af8e..63e978e 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
     "name": "jquery.toc",
-    "version": "0.3.5",
+    "version": "0.4.0",
     "description": "A minimal, tiny jQuery plugin that will generate a table of contents, drawing from headings on the page.",
     "main": "jquery.toc.js",
     "repository": {
diff --git a/toc.jquery.json b/toc.jquery.json
index 8650d7b..7369a93 100644
--- a/toc.jquery.json
+++ b/toc.jquery.json
@@ -8,7 +8,7 @@
         "contents",
         "headings"
     ],
-    "version": "0.3.5",
+    "version": "0.4.0",
     "author": {
         "name": "Nikhil Dabas",
         "url": "http://www.nikhildabas.com/"