feat(core-utils): CB-1068 throttleAsync

webapp/packages/core-utils/src/throttle.ts

@@ -6,6 +6,8 @@
  * you may not use this file except in compliance with the License.
  */
 
+type ThrottleAsync<TResult, TArguments extends any[]> = (...args: TArguments) => Promise<TResult>;
+
 export function throttle<T extends (...args: any[]) => void | Promise<void>>(f: T, delay: number): T {
   let throttle = false;
   let pending = false;
@@ -38,3 +40,52 @@ export function throttle<T extends (...args: any[]) => void | Promise<void>>(f:
     }
   } as T;
 }
+
+export function throttleAsync<
+  TResult,
+  TArguments extends any[],
+  T extends (...args: TArguments) => Promise<TResult>
+>(f: T, delay: number): ThrottleAsync<TResult, TArguments> {
+  let throttle = false;
+  let _resolve: ((result: TResult) => void) | null = null;
+  let _reject: ((reason?: any) => void) | null = null;
+  let functionArgs: TArguments | null = null;
+  let thisObject: any;
+
+  return async function exec(this: any, ...args: TArguments): Promise<TResult> {
+    if (throttle) {
+      functionArgs = args;
+      thisObject = this;
+
+      if (_reject) {
+        _reject();
+      }
+
+      return new Promise<TResult>((resolve, reject) => {
+        _resolve = resolve;
+        _reject = reject;
+      });
+    }
+
+    throttle = true;
+
+    try {
+      return f.apply(this, args);
+    } finally {
+      setTimeout(() => {
+        throttle = false;
+
+        if (functionArgs) {
+          f.apply(thisObject, functionArgs)
+            .then(_resolve)
+            .catch(_reject);
+
+          _resolve = null;
+          _reject = null;
+          thisObject = null;
+          functionArgs = null;
+        }
+      }, delay);
+    }
+  };
+}