Disable heading IDs

docs/USING_ADVANCED.md

@@ -39,18 +39,25 @@ console.log(myMarked('I am using __markdown__.'));
 
 <h2 id="options">Options</h2>
 
-|Member     |Type      |Notes                                                                                                                        |
-|:----------|:---------|:----------------------------------------------------------------------------------------------------------------------------|
-|highlight  |`function`|A function to highlight code blocks. See also: <a href="#highlight">Asynchronous highlighting</a>.|
-|renderer   |`object`  |An object containing functions to render tokens to HTML. See [extensibility](https://github.com/markedjs/marked/blob/master/docs/USING_PRO.md) for more details. Default: `new Renderer()`.|
-|pedantic   |`boolean` |Conform to obscure parts of `markdown.pl` as much as possible. Don't fix original markdown bugs or behavior. Default: `false`.|
-|gfm        |`boolean` |Use approved [GitHub Flavored Markdown (GFM) specification](https://github.github.com/gfm/). Default: `true`.|
-|tables     |`boolean` |Use [GFM Tables extension](https://github.github.com/gfm/#tables-extension-). Requires `gfm` be `true`. Default: `true`.|
-|breaks     |`boolean` |Use GFM [hard](https://github.github.com/gfm/#hard-line-breaks) and [soft](https://github.github.com/gfm/#soft-line-breaks) line breaks. Requires `gfm` be `true`. Default: `false`.|
-|sanitize   |`boolean` |Ignore HTML passed into `markdownString` (sanitize the input). Default: `false`.|
-|smartlists |`boolean` |Use smarter list behavior than those found in `markdown.pl`. Default: `true`.|
-|smartypants|`boolean` |Use "smart" typographic punctuation for things like quotes and dashes. Default: `false`.|
-|xhtml      |`boolean` |Self-close the tags for void elements (&lt;br/&gt;, &lt;img/&gt;, etc.) with a "/" as required by XHTML. Default: `false`.|
+|Member      |Type      |Notes                                                                                                                        |
+|:-----------|:---------|:----------------------------------------------------------------------------------------------------------------------------|
+|baseUrl     |`??`      |Default is `null`                                                                                                            |  
+|breaks      |`boolean` |Use GFM [hard](https://github.github.com/gfm/#hard-line-breaks) and [soft](https://github.github.com/gfm/#soft-line-breaks) line breaks. Requires `gfm` be `true`. Default: `false`|
+|gfm         |`boolean` |Use approved [GitHub Flavored Markdown (GFM) specification](https://github.github.com/gfm/).                                 |
+|headerIds   |`boolean` |Whether to add an `id` attribute to headers. Default: `true`                                                                 |
+|headerPrefix|`string`  |A short string to add as a prefix to the `id` attributes added to headers by default. Default: `empty string`                |
+|highlight   |`function`|A function to highlight code blocks. See also: <a href="#highlight">Asynchronous highlighting</a>.                           |
+|langPrefix  |`??`      |Default is `lang-`
+|mangle      |`boolean` |Default is `true`
+|pedantic    |`boolean` |Conform to obscure parts of `markdown.pl` as much as possible. Don't fix original markdown bugs or behavior. Default: `false`|
+|renderer    |`object`  |An object containing functions to render tokens to HTML. See [extensibility](https://github.com/markedjs/marked/blob/master/docs/USING_PRO.md) for more details. Default: `new Renderer()`|
+|sanitize    |`boolean` |Ignore HTML passed into `markdownString` (sanitize the input). Default: `false`                                              |
+|sanitizer   |`??`      |Default is `null`                                                                                                            |
+|silent      |`boolean` |Default is `false`                                                                                                           |
+|smartlists  |`boolean` |Use smarter list behavior than those found in `markdown.pl`. Default: `true`                                                 |
+|smartypants |`boolean` |Use "smart" typographic punctuation for things like quotes and dashes.                                                       |
+|tables      |`boolean` |Use [GFM Tables extension](https://github.github.com/gfm/#tables-extension-). Requires `gfm` be `true`.                      |
+|xhtml       |`boolean` |Self-close the tags for void elements (&lt;br/&gt;, &lt;img/&gt;, etc.) with a "/" as required by XHTML. Default: `false`    |
 
 <h2 id="highlight">Asynchronous highlighting</h2>
 

lib/marked.js

@@ -823,16 +823,20 @@ Renderer.prototype.html = function(html) {
 };
 
 Renderer.prototype.heading = function(text, level, raw) {
-  return '<h'
-    + level
-    + ' id="'
-    + this.options.headerPrefix
-    + raw.toLowerCase().replace(/[^\w]+/g, '-')
-    + '">'
-    + text
-    + '</h'
-    + level
-    + '>\n';
+  if (this.options.headerIds) {
+    return '<h'
+      + level
+      + ' id="'
+      + this.options.headerPrefix
+      + raw.toLowerCase().replace(/[^\w]+/g, '-')
+      + '">'
+      + text
+      + '</h'
+      + level
+      + '>\n';
+  }
+  // ignore IDs
+  return '<h' + level + '>' + text + '</h' + level + '>\n';
 };
 
 Renderer.prototype.hr = function() {
@@ -1342,22 +1346,23 @@ marked.setOptions = function(opt) {
 };
 
 marked.defaults = {
-  gfm: true,
-  tables: true,
+  baseUrl: null,
   breaks: false,
+  gfm: true,
+  headerIds: true,
+  headerPrefix: '',
+  highlight: null,
+  langPrefix: 'lang-',
+  mangle: true,
   pedantic: false,
+  renderer: new Renderer(),
   sanitize: false,
   sanitizer: null,
-  mangle: true,
-  smartLists: false,
   silent: false,
-  highlight: null,
-  langPrefix: 'lang-',
+  smartLists: false,
   smartypants: false,
-  headerPrefix: '',
-  renderer: new Renderer(),
-  xhtml: false,
-  baseUrl: null
+  tables: true,
+  xhtml: false
 };
 
 /**