Merge branch 'develop' into a11y-improvements

# Conflicts:
#	dist/plyr.js
#	dist/plyr.js.map
#	dist/plyr.min.js
#	dist/plyr.min.js.map
#	dist/plyr.polyfilled.js
#	dist/plyr.polyfilled.js.map
#	dist/plyr.polyfilled.min.js
#	dist/plyr.polyfilled.min.js.map
#	src/js/controls.js
#	src/js/fullscreen.js
#	src/js/plyr.js
#	src/js/ui.js
#	src/js/utils.js

1 files changed, 67 insertions, 0 deletions

diff --git a/src/js/utils/is.js b/src/js/utils/is.js
new file mode 100644
index 00000000..cb2c07c6
--- /dev/null
+++ b/src/js/utils/is.js
@@ -0,0 +1,67 @@
+// ==========================================================================
+// Type checking utils
+// ==========================================================================
+
+const getConstructor = input => (input !== null && typeof input !== 'undefined' ? input.constructor : null);
+
+const instanceOf = (input, constructor) => Boolean(input && constructor && input instanceof constructor);
+
+const is = {
+    object(input) {
+        return getConstructor(input) === Object;
+    },
+    number(input) {
+        return getConstructor(input) === Number && !Number.isNaN(input);
+    },
+    string(input) {
+        return getConstructor(input) === String;
+    },
+    boolean(input) {
+        return getConstructor(input) === Boolean;
+    },
+    function(input) {
+        return getConstructor(input) === Function;
+    },
+    array(input) {
+        return !is.nullOrUndefined(input) && Array.isArray(input);
+    },
+    weakMap(input) {
+        return instanceOf(input, WeakMap);
+    },
+    nodeList(input) {
+        return instanceOf(input, NodeList);
+    },
+    element(input) {
+        return instanceOf(input, Element);
+    },
+    textNode(input) {
+        return getConstructor(input) === Text;
+    },
+    event(input) {
+        return instanceOf(input, Event);
+    },
+    cue(input) {
+        return instanceOf(input, window.TextTrackCue) || instanceOf(input, window.VTTCue);
+    },
+    track(input) {
+        return instanceOf(input, TextTrack) || (!is.nullOrUndefined(input) && is.string(input.kind));
+    },
+    url(input) {
+        return (
+            !is.nullOrUndefined(input) &&
+            /(ftp|http|https):\/\/(\w+:{0,1}\w*@)?(\S+)(:[0-9]+)?(\/|\/([\w#!:.?+=&%@!\-/]))?/.test(input)
+        );
+    },
+    nullOrUndefined(input) {
+        return input === null || typeof input === 'undefined';
+    },
+    empty(input) {
+        return (
+            is.nullOrUndefined(input) ||
+            ((is.string(input) || is.array(input) || is.nodeList(input)) && !input.length) ||
+            (is.object(input) && !Object.keys(input).length)
+        );
+    },
+};
+
+export default is;