@style.tools/async-css

Async CSS and Script Loader

A lightweight asynchronous CSS and Javascript loader.

• Dependency, responsive and timed download and/or render/exec.
• in-view (element in view) based loading.
• requestAnimationFrame and requestIdleCallback (smooth rendering/exec based on CPU)
• Chainable and events.
• localStorage or Cache API based loading (much faster, see css-art.com)
• Async injected stylesheet and script capture via MutationObserver or DOM insert method rewriting.
• Fallback via try {} catch and <noscript rel="css">.
• Google Closure Compiler with Advanced Optimizations based script compression and JSON config compression for Above The Fold optimization.
• HTML data-attribute data-c based JSON config to enable Content-Security-Policy (CSP) with page-based config.
• Performance API timings for debugging and optimization.

Install via npm

npm install @style.tools/async-css --save

Install via PHP Composer

composer require styletools/async-css

The script is optimized to achieve the minimum size possible for above the fold optimization.

Show script sizes of async loader modules

async-core.js Size: 2.04 kb (2089 bytes) Gzip: 0.99 kb (1012 bytes).
event-emitter.js Size: 0.47 kb (482 bytes) Gzip: 0.24 kb (245 bytes).
debug.js Size: 0.13 kb (130 bytes) Gzip: 0.13 kb (135 bytes).
css-loader.js Size: 1.07 kb (1094 bytes) Gzip: 0.63 kb (646 bytes).
js-loader.js Size: 1.83 kb (1876 bytes) Gzip: 1.01 kb (1032 bytes).
inline-js.js Size: 0.38 kb (390 bytes) Gzip: 0.27 kb (278 bytes).
rebase.js Size: 0.12 kb (124 bytes) Gzip: 0.12 kb (124 bytes).
regex.js Size: 0.14 kb (142 bytes) Gzip: 0.14 kb (144 bytes).
vendor.js Size: 0.18 kb (187 bytes) Gzip: 0.17 kb (169 bytes).
api.js Size: 0.25 kb (256 bytes) Gzip: 0.18 kb (187 bytes).
dependency.js Size: 0.71 kb (727 bytes) Gzip: 0.41 kb (418 bytes).
timing.js Size: 0.71 kb (726 bytes) Gzip: 0.41 kb (415 bytes).
inview.js Size: 0.92 kb (944 bytes) Gzip: 0.55 kb (566 bytes).
responsive.js Size: 0.26 kb (267 bytes) Gzip: 0.20 kb (201 bytes).
cache.js Size: 1.35 kb (1381 bytes) Gzip: 0.76 kb (776 bytes).
cache-css.js Size: 0.32 kb (325 bytes) Gzip: 0.24 kb (242 bytes).
cache-js.js Size: 0.05 kb (55 bytes) Gzip: 0.07 kb (71 bytes).
localstorage.js Size: 0.43 kb (438 bytes) Gzip: 0.28 kb (284 bytes).
cache-api.js Size: 0.62 kb (632 bytes) Gzip: 0.34 kb (353 bytes).
xhr.js Size: 0.83 kb (849 bytes) Gzip: 0.49 kb (503 bytes).
cache-update.js Size: 0.15 kb (152 bytes) Gzip: 0.13 kb (134 bytes).
capture.js Size: 1.23 kb (1259 bytes) Gzip: 0.71 kb (723 bytes).
capture-observer.js Size: 0.26 kb (263 bytes) Gzip: 0.20 kb (208 bytes).
capture-insert.js Size: 0.34 kb (348 bytes) Gzip: 0.22 kb (224 bytes).
capture-css.js Size: 0.14 kb (141 bytes) Gzip: 0.13 kb (131 bytes).
capture-js.js Size: 0.07 kb (69 bytes) Gzip: 0.08 kb (87 bytes).
attr-config.js Size: 0.29 kb (293 bytes) Gzip: 0.22 kb (229 bytes).

Documentation is available on docs.style.tools/async-css.

Browser tests

Under construction...

Browser tests provided by BrowserStack.