Project import generated by Copybara.
GitOrigin-RevId: 63746295f1a5ab5a619056791995793d65529e62
diff --git a/node_modules/mdl-ext/src/utils/debounce-function.js b/node_modules/mdl-ext/src/utils/debounce-function.js
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+/**
+ * Debouncing enforces that a function not be called again until a certain
+ * amount of time has passed without it being called.
+ *
+ * @see https://css-tricks.com/the-difference-between-throttling-and-debouncing/
+ * @see https://github.com/webmodules/raf-debounce
+ * @see https://github.com/moszeed/es6-promise-debounce
+ * @see https://gist.github.com/philbirnie/893950093611d5c1dff4246a572cfbeb/
+ * @see https://github.com/SliceMeNice-ES6/event-utils/blob/master/debounce.js
+ * @see https://github.com/jeromedecoster/raf-funcs
+ * @see http://unscriptable.com/2009/03/20/debouncing-javascript-methods/
+ * @see http://davidwalsh.name/javascript-debounce-function
+ *
+ * @param callback the callback
+ * @param threshold optional delay, default to 250 ms, min to 1000/60ms ms
+ * @param context optional context of this, default to global
+ * @return {Function} reference to immediate and cancel
+ */
+const MIN_THRESHOLD = 1000/60;
+
+const debounceFunction = function(callback, threshold=250, context) {
+
+ if(threshold < MIN_THRESHOLD) {
+ threshold = MIN_THRESHOLD;
+ }
+
+ if (!context) {
+ context = this || window;
+ }
+
+ let next = null;
+ let start = 0;
+
+ return function (...args) {
+
+ const cancel = () => {
+ if(next) {
+ window.cancelAnimationFrame(next);
+ next = null;
+ }
+ };
+
+ const execute = () => {
+ cancel();
+ return Reflect.apply(callback, context, args);
+ };
+
+ const later = () => {
+ if (threshold - (Date.now() - start) <= 0) {
+ return execute();
+ }
+ next = window.requestAnimationFrame(later);
+ };
+
+ cancel();
+ start = Date.now();
+ next = window.requestAnimationFrame(later);
+
+ return {
+ cancel: () => cancel(),
+ immediate: () => execute()
+ };
+ };
+};
+
+export default debounceFunction;