1 files changed, 93 insertions, 0 deletions
diff --git a/javascript/videojs/src/js/utils/hooks.js b/javascript/videojs/src/js/utils/hooks.js
new file mode 100644
index 0000000..a6ac8fe
--- /dev/null
+++ b/javascript/videojs/src/js/utils/hooks.js
@@ -0,0 +1,93 @@
+/**
+ * An Object that contains lifecycle hooks as keys which point to an array
+ * of functions that are run when a lifecycle is triggered
+ *
+ * @private
+ */
+const hooks_ = {};
+
+/**
+ * Get a list of hooks for a specific lifecycle
+ *
+ * @param  {string} type
+ *         the lifecycle to get hooks from
+ *
+ * @param  {Function|Function[]} [fn]
+ *         Optionally add a hook (or hooks) to the lifecycle that your are getting.
+ *
+ * @return {Array}
+ *         an array of hooks, or an empty array if there are none.
+ */
+const hooks = function(type, fn) {
+  hooks_[type] = hooks_[type] || [];
+  if (fn) {
+    hooks_[type] = hooks_[type].concat(fn);
+  }
+  return hooks_[type];
+};
+
+/**
+ * Add a function hook to a specific videojs lifecycle.
+ *
+ * @param {string} type
+ *        the lifecycle to hook the function to.
+ *
+ * @param {Function|Function[]}
+ *        The function or array of functions to attach.
+ */
+const hook = function(type, fn) {
+  hooks(type, fn);
+};
+
+/**
+ * Remove a hook from a specific videojs lifecycle.
+ *
+ * @param  {string} type
+ *         the lifecycle that the function hooked to
+ *
+ * @param  {Function} fn
+ *         The hooked function to remove
+ *
+ * @return {boolean}
+ *         The function that was removed or undef
+ */
+const removeHook = function(type, fn) {
+  const index = hooks(type).indexOf(fn);
+
+  if (index <= -1) {
+    return false;
+  }
+
+  hooks_[type] = hooks_[type].slice();
+  hooks_[type].splice(index, 1);
+
+  return true;
+};
+
+/**
+ * Add a function hook that will only run once to a specific videojs lifecycle.
+ *
+ * @param {string} type
+ *        the lifecycle to hook the function to.
+ *
+ * @param {Function|Function[]}
+ *        The function or array of functions to attach.
+ */
+const hookOnce = function(type, fn) {
+  hooks(type, [].concat(fn).map(original => {
+    const wrapper = (...args) => {
+      removeHook(type, wrapper);
+      return original(...args);
+    };
+
+    return wrapper;
+  }));
+};
+
+export {
+  hooks_,
+  hooks,
+  hook,
+  hookOnce,
+  removeHook
+};