X-Cart:CSS and JavaScript optimization
Contents
General info
To optimize operations with CSS and JavaScript, we have added new Smarty tags:
- load_defer
- load_defer_code
Both these tags handle the operations of assembling and outputting of code for JavaScript and CSS. The logic of the tags depends on the store configuration variables:
If these variables are enabled, 'load_defer' assembles the code added to X-Cart templates to a single JS or CSS file, then 'load_defer_code' outputs the assembled code (by including the corresponding JS and CSS files to the page source).
If these variables are disabled, 'load_defer' outputs the code added to X-Cart templates immediately, and 'load_defer_code' doesn't do anything.
Adding JS and CSS code to X-Cart templates
JS and CSS code can be added to X-Cart templates in two ways:
- Included from an external file.
- Entered directly in a template.
In the first case, you should pass the 'file' parameter, which is the path to the JS or CSS file to be included. For example:
{load_defer file="lib/jcarousel.js" type="js"}
{load_defer file="js/popup_open.js" type="js"}
{load_defer file="lib/cluetip/jquery.cluetip.css" type="css"}
{load_defer file="modules/Wishlist/main_carousel.css" type="css"}
In the second case, you should include your JS/CSS code between {capture}...{/capture} tags , and pass the additional 'direct_info' parameter, which contains the code to be assembled. For example:
{capture name=admin_preview_js}
var txt_this_form_is_for_demo_purposes = '{$lng.txt_this_form_is_for_demo_purposes|wm_remove|escape:javascript}';
var txt_this_link_is_for_demo_purposes = '{$lng.txt_this_link_is_for_demo_purposes|wm_remove|escape:javascript}';
{/capture}
{load_defer file="admin_preview_js" direct_info=$smarty.capture.admin_preview_js type="js"}
{capture name=my_css}
<style type="text/css">
#myUserStyle
{background:#212121;}
</style>
{/capture}
{load_defer file="my_css" direct_info=$smarty.capture.my_css type="css"}
You can find code examples in the following X-Cart files:
- skin/common_files/customer/service_js.tpl
- skin/common_files/customer/service_css.tpl
Besides, the above files are the best location for your custom JS code and CSS.
CSS code optimization
CSS is considered optimal when it is entirely declared and called prior to the <body> tag (specifically, between the <head> and </head> tags). Another recommendation is to keep it all in a single file. If these are observed, the style is not going to be rebuilt while loading DOM and the styles if they are specified below.
That is why 'skin/common_files/customer/service_head.tpl' includes the {load_defer_code type="css"} tag. The entire CSS is included earlier, in 'skin/common_files/customer/service_css.tpl'.
For example:
skin/common_files/customer/service_head.tpl
{include file="customer/service_css.tpl"}
... skipped code ...
{load_defer_code type="css"}
skin/common_files/customer/service_css.tpl
{load_defer file="lib/cluetip/jquery.cluetip.css" type="css"}
It is also recommended to use relative paths in such construction as shown below:
url(path_to_css)
Besides, make sure to have no spaces in the 'path_to_css' parameter.
JS code optimization
Regarding JavaScript, assembling and outputting JavaScript code goes in two stages:
- Immediately before the </body> tag.
- Before the <body> tag (specifically, between the <head> and </head> tags).
In the first case, the {load_defer_code type="js"} tag is included into 'skin/common_files/customer/home.tpl', and all the JS is included earlier in other files. For example:
skin/common_files/customer/home.tpl
{include file="customer/content.tpl"}
... skipped code ...
{load_defer_code type="js"}
skin/common_files/customer/content.tpl =>
- skin/common_files/customer/right_bar.tpl =>
- skin/common_files/customer/menu_cart.tpl =>
- skin/common_files/customer/ajax.minicart.tpl
- skin/common_files/customer/menu_cart.tpl =>
{load_defer file="js/ajax.minicart.js" type="js"}
In the second case, {load_defer_code type="js"} tag is included in 'skin/common_files/customer/service_head.tpl', and all the JS is included earlier in 'skin/common_files/customer/service_js.tpl'. For example:
skin/common_files/customer/service_js.tpl
{load_defer file="js/common.js" type="js"}
skin/common_files/customer/service_head.tpl
{include file="customer/service_js.tpl"}
... skipped code ...
{load_defer_code type="js"}
It is highly recommended to place JavaScript code at the bottom, i.e. right above the </body> tag. In this case, the code will be loaded and executed after the browser has built the DOM.
Much of X-Cart functionality does not take this into account and place JavaScript code before the <body> tag, thus making JavaScript code run while the page is being loaded.
Besides that, with the current functionality, it is not always possible to use the 'load_defer' tags, so sometimes JavaScript code is included directly.
"queue" parameter
To improve the flexibility and define a code execution order, we are introducing the "queue" parameter for the load_defer tag (set to 0 by default), which determines the order for the execution of code within a resulting code given by optimizer.
For example, the code in skin/common_files/onload_js.tpl
{load_defer file="onload_js" direct_info=$smarty.capture.onload_js type="js" queue="1"}
Caching for buy_now.tpl and other templates
When working on the design, you can disable caching for buy_now.tpl and other templates. Since version 4.4.3, you can do that by adjusting the 'Use cached buy_now.tpl template calls' option. In version 4.4.2, you can disable caching for buy_now.tpl by manually replacing
$smarty->caching = 2;
with
$smarty->caching = 0;
in 'include/templater/plugins/function.include_cache.php'. The older versions do not use template caching.
Also, when working on the design, you may want to turn off the 'Do not check if templates are changed (Smarty compile_check)' option. This is applicable to versions 4.4.2 and newer.
You can force rebuilding the target files by removing all the 'var/cache/*.css' and 'var/cache/*.js' files (versions 4.4.2 and newer).
To ensure the correct operation of CSS/JS optimizers, make sure that the CSS and JS files are available for reading and writing in the 'var/cache' directory (according to the rules set in the default 'var/.htacess' and 'var/cache/.htaccess'). This also applies to versions 4.4.2 and newer.
