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| |
| <html> |
| <head> |
| <meta name="viewport" content="width=device-width, initial-scale=1"> |
| <title>Remove Comments</title> |
| <link rel="stylesheet" href="doc.css"> |
| </head> |
| <body> |
| <!--#include virtual="_header.html" --> |
| |
| |
| <div id=content> |
| <h1>Remove Comments</h1> |
| |
| <h2>Configuration</h2> |
| <p> |
| The 'Remove Comments' filter is enabled by specifying: |
| <dl> |
| <dt>Apache:<dd><pre class="prettyprint" |
| >ModPagespeedEnableFilters remove_comments</pre> |
| <dt>Nginx:<dd><pre class="prettyprint" |
| >pagespeed EnableFilters remove_comments;</pre> |
| </dl> |
| <p> |
| in the configuration file. To retain comments that have semantic reason to be |
| delivered to the browser, you may specify one more wildcard patterns |
| using <code>RetainComment</code> directives. For example: |
| <dl> |
| <dt>Apache:<dd><pre class="prettyprint" |
| >ModPagespeedRetainComment " google_ad_section*"</pre> |
| <dt>Nginx:<dd><pre class="prettyprint" |
| >pagespeed RetainComment " google_ad_section*";</pre> |
| </dl> |
| </p> |
| |
| <h2>Description</h2> |
| <p> |
| The <code>remove_comments</code> filter eliminates HTML comments, |
| which are often used to document the code or to comment out |
| experiments. Note that this directive applies only to HTML files. |
| CSS comments are eliminated with the |
| <code>rewrite_css</code> filter, and Javascript comments are |
| eliminated with the <code>rewrite_javascript</code> filter. |
| </p> |
| <p> |
| The filter reduces the transfer size of HTML files by removing most HTML |
| comments. Depending on the HTML file, this filter can significantly reduce the |
| number of bytes transmitted on the network. Also note that |
| the <code>RetainComment</code> directive currently only applies to HTML files -- |
| the wildcard pattern is not currently used for retaining CSS or Javascript |
| comments. |
| </p> |
| <p> |
| For example, if the HTML document looks like this: |
| </p> |
| <pre class="prettyprint"> |
| <html> |
| <body> |
| <!-- Display the site logo here --> |
| <img src="logo.png"> |
| <!-- Now show the page contents --> |
| <div>Some content here</div> |
| <!-- Apply IE-specific CSS --> |
| <!-- [if IE ]> |
| <link href="iecss.css" rel="stylesheet" type="text/css"> |
| <![endif]--> |
| <!-- google_ad_section_end -- retained due to RetainComment directive --> |
| </body> |
| </html> |
| </pre> |
| <p> |
| Then PageSpeed, with the above directives specified, will rewrite it into: |
| </p> |
| <pre class="prettyprint"> |
| <html> |
| <body> |
| <img src="logo.png"> |
| <div>Some content here</div> |
| <!-- [if IE ]> |
| <link href="iecss.css" rel="stylesheet" type="text/css"> |
| <![endif]--> |
| <!-- google_ad_section_end -- retained due to RetainComment directive --> |
| </body> |
| </html> |
| </pre> |
| <h3>Example</h3> |
| <p> |
| You can see the filter in action at <code>www.modpagespeed.com</code> on this |
| <a href="https://www.modpagespeed.com/examples/remove_comments.html?ModPagespeed=on&ModPagespeedFilters=remove_comments">example</a>. |
| </p> |
| |
| <h2>Notes</h2> |
| <p> |
| The "Remove Comments" filter is aware of |
| <a href="http://msdn.microsoft.com/en-us/library/ms537512(VS.85).aspx">Internet Explorer conditional comments</a> and does not remove them. |
| </p> |
| |
| <h2>Risks</h2> |
| <p> |
| This filter is low risk for most web pages. Some web pages use comments to |
| embed data or JavaScript, in order to reduce the parse time of the HTML |
| document. Such pages sould disable this filter, as it will remove the |
| comments containing the data or JavaScript that is needed by these web |
| pages. |
| </p> |
| |
| |
| </div> |
| <!--#include virtual="_footer.html" --> |
| </body> |
| </html> |
