@ndcode/min_css_cache
v0.1.0
Published
CSS minimizer, caching front-end with live recompilation
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Build Cache wrapper for minifying CSS files
An NDCODE project.
Overview
The min_css_cache
package exports a single constructor
MinCSSCache(diag)
which must be called with the new
operator. The resulting cache object stores
the utf-8
-encoded text of CSS files loaded from disk and minified.
See the build_cache
, disk_build
, and clean-css
packages for more
information. The MinCSSCache
object is essentially a wrapper object which
routes the request between these packages, to ensure that the minified CSS text
is either retrieved from RAM or minified from a source file as required.
Calling API
Suppose one has a MinCSSCache
instance named mcc
. It behaves somewhat like
an ES6 Map
object, except that it only has the mcc.get()
function, because
new objects are added to the cache by attempting to get
them.
The interface for the MinCSSCache
-provided instance function mcc.get()
is:
await mcc.get(key)
— retrieves the object stored under key
, where
key
is the on-disk pathname to a CSS file. A Buffer
object is returned,
containing the utf-8
-encoded text resulting from running clean-css
on the
source file. The pathname and the returned result are cached for future reuse.
Before returning the cached copy, the existence and modification time of the
CSS file on disk is checked to make sure that the cache is up-to-date.
Otherwise, if the file doesn't exist an ENOENT
exception is thrown, or if the
file exists it is loaded and minified and the cache updated for next time. The
minification is via disk, and skipped if an up-to-date disk result is present.
About dependencies
The min_css_cache
is in NDCODE org-scope, as in @ndcode/min_css_cache
. We
also have in NDCODE org-scope, some lightly modified versions of popular
packages such as clean-css
, with added NDCODE hooks. Packages such as this
one, which simply use clean-css
in a standard way without using the NDCODE
hooks, still depend on @ndcode/clean-css
for consistency. This means that
when embedded in an NDCODE project, only one copy of each dependency is loaded.
If this isn't desired, please feel free to fork the package and adjust it.
About diagnostics
The diag
argument to the constructor is a bool
, which if true
causes
messages to be printed via console.log()
for all activities except for the
common case of retrieval when the object is already up-to-date. A diag
value
of undefined
is treated as false
, thus it can be omitted in the usual case.
To be implemented
The clean-css
package is called with standard NDCODE options. This is part of
the reason to have min_css_cache
, so as to provide a consistent interface to
minifiers for JavaScript, CSS, SVG and so on. However, if some control of the
underlying minifier is needed in future, we could add an options
object to
pass through, in which we'd inject our NDCODE options where not overridden.
It is intended that we will shortly add a timer function (or possibly just a
function that the user should call periodically) to flush built templates from
the cache after a stale time. There is otherwise no way to delete an object
from the cache, except by first deleting it on disk, then trying to get
it.
GIT repository
The development version can be cloned, downloaded, or browsed with gitweb
at:
https://git.ndcode.org/public/min_css_cache.git
License
All of our NPM packages are MIT licensed, please see LICENSE in the repository.
Contributions
The caching system is under active development (and is part of a larger project that is also under development) and thus the API is tentative. Please go ahead and incorporate the system into your project, or try out our example webserver built on the system, subject to the caution that the API could change. Please send us your experience and feedback, and let us know of improvements you make.
Contact: Nick Downing [email protected]