Preserving URLs in HTML

PageSpeed filters often modify the URLs of resources in HTML pages. This is generally harmless but it has the potential to break pages whose JavaScript expects to read or modify the URLs in the page.

ImagePreserveURLs, CssPreserveURLs, and JsPreserveURLs will suppress URL rewriting actions for the respective resource types. Those filters that require modifications to the URL are disabled by the preserve directives.

Note: Even though resource URLs are unchanged that does not mean that they cannot still be optimized. For instance, InPlaceResourceOptimization still works since it does not alter URLs. Turning on in place resource optimization is recommended when enabling any of the options to preserve URLs. In version 1.9.32.1 and later in place resource optimization is enabled by default.

Enabling ImagePreserveURLs will forbid the use of the following filters: inline_preview_images, lazyload_images, extend_cache_images, inline_images, and sprite_images.

Enabling CssPreserveURLs will forbid the use of the following filters: combine_css, extend_cache_css, inline_css, inline_import_to_link, and outline_css.

Enabling JsPreserveURLs will forbid the use of the following filters: canonicalize_javascript_libraries, combine_javascript, defer_javascript, extend_cache_scripts, inline_javascript, and outline_javascript.