Merge pull request #2 from mrmartineau/master

add matchMedia shim

readme.md

@@ -21,6 +21,7 @@ Create a JavaScript shim set using node.
 - **EventListener** (EventListener polyfill – [Jonathan Neal](https://github.com/jonathantneal/EventListener))
 - **Document.getElementsByClassName** (getElementsByClassName polyfill – [SitePoint](http://www.sitepoint.com/5-useful-functions-missing-in-javascript/))
 - **String.trim** (`String.prototype.trim()` – [MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim))
+- **matchMedia** (`matchMedia()` – [MDN](https://developer.mozilla.org/en-US/docs/Web/API/Window/matchMedia))
 
 ### Install:
 

shims/matchMedia.js

@@ -0,0 +1,46 @@
+/*! matchMedia() polyfill - Test a CSS media type/query in JS. Authors & copyright (c) 2012: Scott Jehl, Paul Irish, Nicholas Zakas, David Knight. Dual MIT/BSD license */
+
+window.matchMedia || (window.matchMedia = function() {
+    "use strict";
+
+    // For browsers that support matchMedium api such as IE 9 and webkit
+    var styleMedia = (window.styleMedia || window.media);
+
+    // For those that don't support matchMedium
+    if (!styleMedia) {
+        var style       = document.createElement('style'),
+            script      = document.getElementsByTagName('script')[0],
+            info        = null;
+
+        style.type  = 'text/css';
+        style.id    = 'matchmediajs-test';
+
+        script.parentNode.insertBefore(style, script);
+
+        // 'style.currentStyle' is used by IE <= 8 and 'window.getComputedStyle' for all other browsers
+        info = ('getComputedStyle' in window) && window.getComputedStyle(style, null) || style.currentStyle;
+
+        styleMedia = {
+            matchMedium: function(media) {
+                var text = '@media ' + media + '{ #matchmediajs-test { width: 1px; } }';
+
+                // 'style.styleSheet' is used by IE <= 8 and 'style.textContent' for all other browsers
+                if (style.styleSheet) {
+                    style.styleSheet.cssText = text;
+                } else {
+                    style.textContent = text;
+                }
+
+                // Test if media query is true or false
+                return info.width === '1px';
+            }
+        };
+    }
+
+    return function(media) {
+        return {
+            matches: styleMedia.matchMedium(media || 'all'),
+            media: media || 'all'
+        };
+    };
+}());