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richtr/style_scoped_shim.js

Created November 8, 2012 15:12
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<style scoped> polyfill
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style_scoped_shim.js
/*!
* <style scoped> shim
* http://github.com/richtr
*
* Copyright 2012 Rich Tibbett
* Released under the MIT license
* http://opensource.org/licenses/MIT
*
* Date: 8th November 2012
*/
/*
* DESCRIPTION:
* ------------
*
* Javascript shim for <style scoped> elements.
*
* Reference specification ->
*
* http://www.whatwg.org/specs/web-apps/current-work/multipage/semantics.html#attr-style-scoped
*
* Demo page ->
*
* http://fiddle.jshell.net/RZ99U/1/show/light/
*
* USAGE:
* ------
*
* 1. Add this file anywhere in your web page (outside of any load event handlers):
*
* <script type="text/javascript" src="style_scoped_shim.js"></script>
*
*
* 2. Use <style scoped> elements as normal
*
* See the test page linked above for a live example.
*
*/
(function() {
document.addEventListener('DOMContentLoaded', function() {
// Don't run if the UA implicitly supports <style scoped>
var testEl = document.createElement("style");
if (testEl.scoped !== undefined && testEl.scoped !== null) return;
var rewriteCSS = function(el) {
el._scopedStyleApplied = true;
var elName = "scopedstylewrapper";
var elId = "s" + (Math.floor(Math.random() * 1e15) + 1);
var uid = "." + elId;
// Wrap a custom HTML container around style[scoped]'s parent node
var container = el.parentNode;
if(container == document.body) {
uid = "body"; // scope CSS rules to <body>
} else {
var parent = container.parentNode;
var wrapper = document.createElement(elName);
wrapper.className = elId;
parent.replaceChild(wrapper, container);
wrapper.appendChild(container);
}
// Prefix all CSS rules with uid
var rewrittenCSS = el.textContent.replace(/(((?:(?:[^,{]+),?)*?)\{(?:([^}:]*):?([^};]*);?)*?\};*)/img, uid + " $1");
// <style scoped> @-directives rules from WHATWG specification
// Remove added uid prefix from all CSS @-directives commands
// since we have no way of scoping @-directives yet
// e.g. .scopingClass @font-face { ... } does not currently work :(
rewrittenCSS = rewrittenCSS.replace(new RegExp(uid + "\\s+(@[\\w|-]+)" , 'img'), "$1");
// Remove @global (to make the @global CSS rule work globally)
rewrittenCSS = rewrittenCSS.replace("@global", "");
// Ignore @page directives (not allowed in <style scoped>)
rewrittenCSS = rewrittenCSS.replace("@page", ".notAllowedInScopedCSS @page");
el.textContent = rewrittenCSS;
};
var extractScopedStyles = function( root ) {
// Obtain style[scoped] elements from page
if(root.nodeType !== Node.ELEMENT_NODE && root.nodeType !== Node.DOCUMENT_NODE)
return;
var els = root.querySelectorAll('style[scoped]');
for (var i = 0, l = els.length; i < l; i++) {
if(!els[i]._scopedStyleApplied)
rewriteCSS(els[i]);
}
};
// Process scoped stylesheets from current page
extractScopedStyles(document);
// Listen for scoped stylesheet injection
document.addEventListener('DOMNodeInserted', function(e) {
var el = e.target;
if (el.tagName === "STYLE" && (el.getAttribute("scoped") !== undefined &&
el.getAttribute("scoped") !== null) && !el._scopedStyleApplied) {
rewriteCSS(el);
}
// Process nested style[scope] elements (if any)
extractScopedStyles(el);
}, false);
}, false);
})();
@SpadarShut
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Why not add a custom attribute to the style's parent element ans prefix selectors with according [attribute-selector]?

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