Jay Harris is Cpt. LoadTest

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Google Syntax Highlighter is a simple tool that allows bloggers to easily display code in a format that is familiar end users. The tool renders the code in a very consumable fashion that includes colored syntax highlighting, line highlighting, and line numbers.

This is an example of how Google
Syntax Highlighter can highlight and display syntax
to you, the end user
public void HelloWorld()
  // I have some comments
  Console.WriteLine("Hello, World!");

It is purely a client-side tool, as all of the processing is done strictly within the browser through JavaScript. There is no server-side processing. Since it is all JavaScript, you don't need special Copy/Paste plugins and macros installed to your favorite IDE or your blog authoring tool. (I am leery of random plugins and installing them into the software that I use to feed my family.) To including code in your blog post, copy your code from Visual Studio, Notepad, Flash, Firebug, or any tool that displays text, and paste it in to your post. As of v1.5.1, Google Syntax Highlighter supports C, C++, C#, CSS, Delphi, HTML, Java, JavaScript, PHP, Pascal, Python, Ruby, SQL, VB, VB.NET, XML, XSLT, and all of this is just what comes out of the box.

Setting Up Syntax Highlighter

To get Syntax Highlighter running on your blog, download the latest version of the RAR archive and extract the code. The archive contains a parent folder, dp.SyntaxHighlighter, with three child folders:

  \Scripts         //Production-ready (Compressed) scripts
  \Styles          //CSS
  \Uncompressed    //Human-readable (Uncompressed/Debug) scripts

Once the archive is extracted, upload dp.SyntaxHighlighter to your blog. Feel free to rename the folder if you like, though I did not. It is not necessary to upload the Uncompressed folder and its files; they are best used for debugging or for viewing the code, as the files in the Scripts folder have been compressed to reduce bandwidth by having most of their whitespace removed.

After you have uploaded the files, you will need to add script and style references to your site's HTML. This is code is not for your posts, but rather for your blog template. In DasBlog, I place this code in the <HEAD> block of my homeTemplate.blogtemplate file. Remember to change the file paths to match the path to where you uploaded the code.

<link type="text/css" rel="stylesheet"
<script language="javascript" src="dp.SyntaxHighlighter/Scripts/shCore.js"></script>
<script language="javascript" src="dp.SyntaxHighlighter/Scripts/shBrushCSharp.js"></script>
<script language="javascript" src="dp.SyntaxHighlighter/Scripts/shBrushXml.js"></script>
<script language="javascript">
window.onload = function () {
  dp.SyntaxHighlighter.ClipboardSwf = 'dp.SyntaxHighlighter/Scripts/clipboard.swf';

To make the tool most efficient, including minimizing the code download by the client browser, highlighting is only enabled for the languages that you specify. The highlighting rules for each language is available through a file referred to as a Brush. The code sample above enables only C# and XML/HTML by including the core file, shCore.js, the C# brush, shBrushCSharp.js and the XML/HTML brush, shBrushXml.js. A unique brush file is available for each of the supported languages, and only the core file is required. These brushes are located in your Scripts directory (the human-readable version is in the Uncompressed folder). Include only the brushes that you like; if you forgot a language brush, the code will still display on your page, but as unformatted text.

<!-- Unformatted HTML Code / No Brush -->
<p id="greeting">Hi, mom & dad!</p>
<!-- Formatted HTML Code -->
<p id="greeting">Hi, mom & dad!</p>

Making Syntax Highlighter Go

Now that the application is deployed to the site, how does it get applied to a post? Paste the code into the HTML view of your post, inside of a <PRE> tag. Create a name attribute on your tag with a value of code, and a class attribute set to the language and options you are using.

<pre name="code" class="c-sharp">
  public void HelloWorld()
    Console.WriteLine("Hello, World!");

One catch is the code must be first made HTML-safe. All angle-brackets, <tag>, must be converted to their HTML equivalent, &lt;tag&gt;, as well as ampersands, & to &amp;. I also find it helpful if your code-indentation uses two-spaces, rather than tabs.

<!-- Pre-converted code -->
<p>Hi, mom & dad!</p>
<!-- Converted code -->
<pre name="code" class="html">
  &lt;p&gt;Hi, mom &amp; dad!&lt;/p&gt;

The class attribute is made up of both language and option aliases. These aliases consist of one language followed by your desired options, all in a colon delimited list.


The value of language is any of Syntax Highlighter's defined language aliases, such as c#, csharp, or c-sharp for C#, or rb, ruby, rails, or ror for Ruby. See: full list of available languages.

Options allow for such things as turning off the plain text / copy / about controls (nocontrols), turning off the line number gutter (nogutter), or specifying the number of the first line (firstline[n]). A JavaScript code block with no controls header, and starting the line numbering at 34 would have a class attribute value of class="js:nocontrols:linenumber[34]". See: full list of available options.

Extending Syntax Highlighter

Because Google Syntax Highlighter is entirely in JavaScript, you have access to all of the code. Edit it however you like to suit your needs. Additionally, brushes are very easy to create, and include little more than a list of a highlighted language's keywords in a string and an array of language aliases. Creating a brush for ActionScript or QBasic would not take much time. Language brushes exist in the wild for Perl, DOS Batch, and ColdFusion.

In a future post I plan on discussing Brush Creation in depth through creating a brush for ActionScript.

Comparing Syntax Highlighter to Others

I am a fan of this tool, though that should be obvious considering it is what I use on this blog. I like how readable the code is, how extendable it is, and how easy it is to use. I don't like its compatibility--or lack thereof--with RSS; since all of the work is done in JavaScript, and RSS doesn't do JavaScript, there is no syntax highlighting, numbers, or options within a feed, though the code formatting is still maintained. Other tools, like the CopySourceAsHtml plugin for Visual Studio or Insert Code Snippet for Windows Live Writer convert your code into formatted HTML, where all of the syntax highlighting is applied through HTML attributes and embedded CSS. Their methods are much easier than Syntax Highlighter, since there are no stylesheets or JavaScript files to include in your HTML, and you don't have to worry about making your code HTML-safe. Also, their method works in RSS feeds. However, there isn't the same level of control. Through Syntax Highlighter's extendibility, I can theme my code views, such as if I wanted them to look like my personal Visual Studio theme. Through Syntax Highlighter, I can also make changes at a later time, and those changes will immediately reflected in all past posts, whereas making modifications to the HTML/embedded CSS pattern is much more difficult.

Final Thoughts

I like CopySourceAsHtml in Visual Studio. I used it for years on this blog. But I code in more languages than VB.Net or C#, and the plugin isn't available within the Flash or LoadRunner IDE. I was also frustrated with pasting my code in, only to find that it was too wide for my blog theme's margins, and would have to go back to Visual Studio, change my line endings, and repeat the process. I'm sticking with Google Syntax Highlighter. It works for all of my languages (as soon as I finish writing my ActionScript brush), and when my line endings are too long, I simply change my HTML. And in my HTML, my code still looks like code, rather than a mess of embedded style. I have to sacrifice RSS formatting, but as a presentation developer that is very particular about his HTML, I am glad for the customization and control.

Monday, 24 November 2008 10:41:50 (Eastern Standard Time, UTC-05:00)  #    Comments [9] - Trackback

Monday, 24 November 2008 11:56:15 (Eastern Standard Time, UTC-05:00)
Can you use this on Blogger / Blogspot?
Monday, 24 November 2008 12:41:23 (Eastern Standard Time, UTC-05:00)
Yes. This works on Blogger, as well. Insert the following new line of code between your ClipboardSwf and HighlightAll calls (See the Setting Up SyntaxHighlighter section of this post):


The SyntaxHighlighter project wiki has a entry specific to this issue.

Monday, 24 November 2008 13:57:09 (Eastern Standard Time, UTC-05:00)
Thanks for the heads-up, I had never heard of this library before.
Monday, 24 November 2008 22:02:20 (Eastern Standard Time, UTC-05:00)
I have switched back to using GSH with LiveWriter for my blog. What I hadn't realized was that with the "Insert Code Snippet" plugin for LiveWriter, I couldn't even copy the code to the clipboard. With GSH, I can. Thank you GSH! You make my blog shiny.

Monday, 20 July 2009 05:30:24 (Eastern Daylight Time, UTC-04:00)
Thank you so much! this is what I was looking for, Excellent!!!
Sunday, 27 September 2009 09:18:58 (Eastern Daylight Time, UTC-04:00)
Thanks mate!I was looking for that solution nearly all day!I love your blog,awesome!!!
Can I copy this article on my blog?If,yes we can exchange useful articles in the future?
Monday, 01 March 2010 07:14:56 (Eastern Standard Time, UTC-05:00)
I'm looking for link partners to build 3 way link exchange network.We all will get 1 way links and all the web sites in the network are high quality,aged and with good PR.In our network we have more then 400 web site already.Some of them are highly visited job boards,comparision sites and quality blogs.
Sunday, 06 June 2010 21:02:58 (Eastern Daylight Time, UTC-04:00)
Thanks for sharing, really like your view. I can see that you are putting a lot of time and effort into your blog. I have bookmarked this page and I love to share this with my friends and circle of influence.
Monday, 14 June 2010 06:42:46 (Eastern Daylight Time, UTC-04:00)
Just a suggestion, would like to view these via RSS Feed!
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